A leap year starting on Sunday is any year with 366 days (i.e. it includes 29 February) that begins on Sunday, 1 January, and ends on Monday, 31 December. Its dominical letters hence are AG. The most recent year of such kind was 2012 and the next one will be 2040 in the Gregorian calendar[1] or, likewise 2024 and 2052 in the obsolete Julian calendar.
This is the only leap year with three occurrences of Friday the 13th: those three in this leap year occur three months (13 weeks) apart: in January, April, and July. Common years starting on Thursday share this characteristic, in the months of February, March, and November. Leap years starting on Wednesday also share the characteristic of three Friday the 13ths occurring three months (13 weeks) apart, wherein the third one occurs in the month of March, while the other two occur in September and December in the common year preceding that type of year.
In this type of year, all dates (except 29 February) fall on their respective weekdays the maximal 58 times in the 400 year Gregorian calendar cycle. Leap years starting on Friday share this characteristic. Additionally, these types of years are the only ones which contain 54 different calendar weeks (2 partial, 52 in full) in areas of the world where Monday is considered the first day of the week.
Calendars
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Calendar for any leap year starting on Sunday, presented as common in many English-speaking areas |
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January
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03 |
04 |
05 |
06 |
07
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08 |
09 |
10 |
11 |
12 |
13 |
14
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15 |
16 |
17 |
18 |
19 |
20 |
21
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22 |
23 |
24 |
25 |
26 |
27 |
28
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29 |
30 |
31
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February
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03 |
04
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05 |
06 |
07 |
08 |
09 |
10 |
11
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12 |
13 |
14 |
15 |
16 |
17 |
18
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19 |
20 |
21 |
22 |
23 |
24 |
25
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26 |
27 |
28 |
29 |
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March
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03
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04 |
05 |
06 |
07 |
08 |
09 |
10
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11 |
12 |
13 |
14 |
15 |
16 |
17
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18 |
19 |
20 |
21 |
22 |
23 |
24
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25 |
26 |
27 |
28 |
29 |
30 |
31
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April
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03 |
04 |
05 |
06 |
07
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08 |
09 |
10 |
11 |
12 |
13 |
14
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15 |
16 |
17 |
18 |
19 |
20 |
21
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22 |
23 |
24 |
25 |
26 |
27 |
28
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29 |
30 |
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May
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03 |
04 |
05
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06 |
07 |
08 |
09 |
10 |
11 |
12
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13 |
14 |
15 |
16 |
17 |
18 |
19
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20 |
21 |
22 |
23 |
24 |
25 |
26
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27 |
28 |
29 |
30 |
31
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June
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02
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03 |
04 |
05 |
06 |
07 |
08 |
09
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10 |
11 |
12 |
13 |
14 |
15 |
16
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17 |
18 |
19 |
20 |
21 |
22 |
23
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24 |
25 |
26 |
27 |
28 |
29 |
30
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July
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03 |
04 |
05 |
06 |
07
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08 |
09 |
10 |
11 |
12 |
13 |
14
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15 |
16 |
17 |
18 |
19 |
20 |
21
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22 |
23 |
24 |
25 |
26 |
27 |
28
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29 |
30 |
31
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August
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03 |
04
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05 |
06 |
07 |
08 |
09 |
10 |
11
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12 |
13 |
14 |
15 |
16 |
17 |
18
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19 |
20 |
21 |
22 |
23 |
24 |
25
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26 |
27 |
28 |
29 |
30 |
31
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September
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01
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02 |
03 |
04 |
05 |
06 |
07 |
08
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09 |
10 |
11 |
12 |
13 |
14 |
15
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16 |
17 |
18 |
19 |
20 |
21 |
22
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23 |
24 |
25 |
26 |
27 |
28 |
29
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30 |
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October
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03 |
04 |
05 |
06
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07 |
08 |
09 |
10 |
11 |
12 |
13
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14 |
15 |
16 |
17 |
18 |
19 |
20
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21 |
22 |
23 |
24 |
25 |
26 |
27
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28 |
29 |
30 |
31
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November
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01 |
02 |
03
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04 |
05 |
06 |
07 |
08 |
09 |
10
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11 |
12 |
13 |
14 |
15 |
16 |
17
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18 |
19 |
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21 |
22 |
23 |
24
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25 |
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27 |
28 |
29 |
30 |
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December
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Su
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Mo
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Tu
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We
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Th
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Fr
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Sa
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01
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02 |
03 |
04 |
05 |
06 |
07 |
08
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09 |
10 |
11 |
12 |
13 |
14 |
15
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16 |
17 |
18 |
19 |
20 |
21 |
22
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23 |
24 |
25 |
26 |
27 |
28 |
29
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30 |
31
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ISO 8601-conformant calendar with week numbers for any leap year starting on Sunday (dominical letter AG) |
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January
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
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52
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01
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01
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02 |
03 |
04 |
05 |
06 |
07 |
08
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02
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09 |
10 |
11 |
12 |
13 |
14 |
15
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03
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16 |
17 |
18 |
19 |
20 |
21 |
22
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04
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23 |
24 |
25 |
26 |
27 |
28 |
29
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05
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30 |
31
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February
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
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05
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01 |
02 |
03 |
04 |
05
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06
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06 |
07 |
08 |
09 |
10 |
11 |
12
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07
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13 |
14 |
15 |
16 |
17 |
18 |
19
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08
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20 |
21 |
22 |
23 |
24 |
25 |
26
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09
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27 |
28 |
29 |
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March
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
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09
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01 |
02 |
03 |
04
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10
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05 |
06 |
07 |
08 |
09 |
10 |
11
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11
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12 |
13 |
14 |
15 |
16 |
17 |
18
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12
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19 |
20 |
21 |
22 |
23 |
24 |
25
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13
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26 |
27 |
28 |
29 |
30 |
31
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April
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
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13
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01
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14
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02 |
03 |
04 |
05 |
06 |
07 |
08
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15
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09 |
10 |
11 |
12 |
13 |
14 |
15
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16
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16 |
17 |
18 |
19 |
20 |
21 |
22
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17
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23 |
24 |
25 |
26 |
27 |
28 |
29
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18
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30 |
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May
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
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18
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01 |
02 |
03 |
04 |
05 |
06
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19
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07 |
08 |
09 |
10 |
11 |
12 |
13
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20
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14 |
15 |
16 |
17 |
18 |
19 |
20
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21
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21 |
22 |
23 |
24 |
25 |
26 |
27
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22
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28 |
29 |
30 |
31
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June
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
|
22
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01 |
02 |
03
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23
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04 |
05 |
06 |
07 |
08 |
09 |
10
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24
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11 |
12 |
13 |
14 |
15 |
16 |
17
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25
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18 |
19 |
20 |
21 |
22 |
23 |
24
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26
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25 |
26 |
27 |
28 |
29 |
30 |
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July
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
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26
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01
|
27
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02 |
03 |
04 |
05 |
06 |
07 |
08
|
28
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09 |
10 |
11 |
12 |
13 |
14 |
15
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29
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16 |
17 |
18 |
19 |
20 |
21 |
22
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30
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23 |
24 |
25 |
26 |
27 |
28 |
29
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31
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30 |
31
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August
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
|
31
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|
01 |
02 |
03 |
04 |
05
|
32
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06 |
07 |
08 |
09 |
10 |
11 |
12
|
33
|
13 |
14 |
15 |
16 |
17 |
18 |
19
|
34
|
20 |
21 |
22 |
23 |
24 |
25 |
26
|
35
|
27 |
28 |
29 |
30 |
31
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September
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Wk
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Mo
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Tu
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We
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Th
|
Fr
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Sa
|
Su
|
35
|
|
|
|
|
|
01 |
02
|
36
|
03 |
04 |
05 |
06 |
07 |
08 |
09
|
37
|
10 |
11 |
12 |
13 |
14 |
15 |
16
|
38
|
17 |
18 |
19 |
20 |
21 |
22 |
23
|
39
|
24 |
25 |
26 |
27 |
28 |
29 |
30
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|
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October
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
|
40
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01 |
02 |
03 |
04 |
05 |
06 |
07
|
41
|
08 |
09 |
10 |
11 |
12 |
13 |
14
|
42
|
15 |
16 |
17 |
18 |
19 |
20 |
21
|
43
|
22 |
23 |
24 |
25 |
26 |
27 |
28
|
44
|
29 |
30 |
31
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November
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
|
44
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|
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01 |
02 |
03 |
04
|
45
|
05 |
06 |
07 |
08 |
09 |
10 |
11
|
46
|
12 |
13 |
14 |
15 |
16 |
17 |
18
|
47
|
19 |
20 |
21 |
22 |
23 |
24 |
25
|
48
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26 |
27 |
28 |
29 |
30 |
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December
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Wk
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Mo
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Tu
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We
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Th
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Fr
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Sa
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Su
|
48
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01 |
02
|
49
|
03 |
04 |
05 |
06 |
07 |
08 |
09
|
50
|
10 |
11 |
12 |
13 |
14 |
15 |
16
|
51
|
17 |
18 |
19 |
20 |
21 |
22 |
23
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52
|
24 |
25 |
26 |
27 |
28 |
29 |
30
|
01
|
31
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Applicable years
edit
Gregorian Calendar
edit
Leap years that begin on Sunday, along with those starting on Friday, occur most frequently: 15 of the 97 (≈ 15.46%) total leap years in a 400-year cycle of the Gregorian calendar. Thus, their overall occurrence is 3.75% (15 out of 400).
400-year cycle
0–99
|
12 |
40 |
68 |
96
|
100–199
|
108 |
136 |
164 |
192
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200–299
|
204 |
232 |
260 |
288
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300–399
|
328 |
356 |
384 |
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Julian Calendar
edit
Like all leap year types, the one starting with 1 January on a Sunday occurs exactly once in a 28-year cycle in the Julian calendar, i.e., in 3.57% of years. As the Julian calendar repeats after 28 years, it will also repeat after 700 years, i.e., 25 cycles. The formula gives the year's position in the cycle ((year + 8) mod 28) + 1).
Holidays
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International
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Roman Catholic Solemnities
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Australia and New Zealand
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British Isles
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United States
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References
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