# 800 (number)

(Redirected from 803 (number))

800 (eight hundred) is the natural number following 799 and preceding 801.

 ← 799 800 801 →
Cardinaleight hundred
Ordinal800th
(eight hundredth)
Factorization25 × 52
Greek numeralΩ´
Roman numeralDCCC
Binary11001000002
Ternary10021223
Senary34126
Octal14408
Duodecimal56812

It is the sum of four consecutive primes (193 + 197 + 199 + 211). It is a Harshad number, an Achilles number and the area of a square with diagonal 40.[1]

## Integers from 801 to 899

### 820s

• 820 = 22 × 5 × 41, triangular number, smallest triangular number that starts with the digit 8[19] Harshad number, happy number, repdigit (1111) in base 9
• 821 = prime number, twin prime, Chen prime, Eisenstein prime with no imaginary part, lazy caterer number (sequence A000124 in the OEIS), prime quadruplet with 823, 827, 829
• 822 = 2 × 3 × 137, sum of twelve consecutive primes (43 + 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79 + 83 + 89 + 97), sphenic number, member of the Mian–Chowla sequence[20]
• 823 = prime number, twin prime, lucky prime, the Mertens function of 823 returns 0, prime quadruplet with 821, 827, 829
• 824 = 23 × 103, refactorable number, sum of ten consecutive primes (61 + 67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103), the Mertens function of 824 returns 0, nontotient
• 825 = 3 × 52 × 11, Smith number,[21] the Mertens function of 825 returns 0, Harshad number
• 826 = 2 × 7 × 59, sphenic number, number of partitions of 29 into parts each of which is used a different number of times[22]
• 827 = prime number, twin prime, part of prime quadruplet with {821, 823, 829}, sum of seven consecutive primes (103 + 107 + 109 + 113 + 127 + 131 + 137), Chen prime, Eisenstein prime with no imaginary part, strictly non-palindromic number[23]
• 828 = 22 × 32 × 23, Harshad number, triangular matchstick number[24]
• 829 = prime number, twin prime, part of prime quadruplet with {827, 823, 821}, sum of three consecutive primes (271 + 277 + 281), Chen prime, centered triangular number

### 830s

• 830 = 2 × 5 × 83, sphenic number, sum of four consecutive primes (197 + 199 + 211 + 223), nontotient, totient sum for first 52 integers
• 831 = 3 × 277, number of partitions of 32 into at most 5 parts[25]
• 832 = 26 × 13, Harshad number, member of the sequence Horadam(0, 1, 4, 2)[26]
• 833 = 72 × 17, octagonal number (sequence A000567 in the OEIS), a centered octahedral number[27]
• 834 = 2 × 3 × 139, cake number, sphenic number, sum of six consecutive primes (127 + 131 + 137 + 139 + 149 + 151), nontotient
• 835 = 5 × 167, Motzkin number[28]
• 836 = 22 × 11 × 19, weird number
• 837 = 33 × 31, the 36th generalized heptagonal number[29]
• 838 = 2 × 419, palindromic number, number of distinct products ijk with 1 <= i<j<k <= 23[30]
• 839 = prime number, safe prime,[31] sum of five consecutive primes (157 + 163 + 167 + 173 + 179), Chen prime, Eisenstein prime with no imaginary part, highly cototient number[32]

### 840s

• 840 = 23 × 3 × 5 × 7, highly composite number,[33] smallest number divisible by the numbers 1 to 8 (lowest common multiple of 1 to 8), sparsely totient number,[34] Harshad number in base 2 through base 10, idoneal number, balanced number,[35] sum of a twin prime (419 + 421). With 32 distinct divisors, it is the number below 1000 with the largest amount of divisors.
• 841 = 292 = 202 + 212, sum of three consecutive primes (277 + 281 + 283), sum of nine consecutive primes (73 + 79 + 83 + 89 + 97 + 101 + 103 + 107 + 109), centered square number,[36] centered heptagonal number,[37] centered octagonal number[38]
• 842 = 2 × 421, nontotient, 842!! - 1 is prime,[39] number of series-reduced trees with 18 nodes[40]
• 843 = 3 × 281, Lucas number[41]
• 844 = 22 × 211, nontotient, smallest 5 consecutive integers which are not squarefree are: 844 = 22 × 211, 845 = 5 × 132, 846 = 2 × 32 × 47, 847 = 7 × 112 and 848 = 24 × 53 [42]
• 845 = 5 × 132, concentric pentagonal number,[43] number of emergent parts in all partitions of 22 [44]
• 846 = 2 × 32 × 47, sum of eight consecutive primes (89 + 97 + 101 + 103 + 107 + 109 + 113 + 127), nontotient, Harshad number
• 847 = 7 × 112, happy number, number of partitions of 29 that do not contain 1 as a part[45]
• 848 = 24 × 53, untouchable number
• 849 = 3 × 283, the Mertens function of 849 returns 0, blum integer

### 860s

• 860 = 22 × 5 × 43, sum of four consecutive primes (199 + 211 + 223 + 227), Hoax number[56]
• 861 = 3 × 7 × 41, sphenic number, triangular number,[19] hexagonal number,[57] Smith number[21]
• 862 = 2 × 431, lazy caterer number (sequence A000124 in the OEIS)
• 863 = prime number, safe prime,[31] sum of five consecutive primes (163 + 167 + 173 + 179 + 181), sum of seven consecutive primes (107 + 109 + 113 + 127 + 131 + 137 + 139), Chen prime, Eisenstein prime with no imaginary part, index of prime Lucas number[58]
• 864 = 25 × 33, Achilles number, sum of a twin prime (431 + 433), sum of six consecutive primes (131 + 137 + 139 + 149 + 151 + 157), Harshad number
• 865 = 5 × 173,
• 866 = 2 × 433, nontotient, number of one-sided noniamonds,[59] number of cubes of edge length 1 required to make a hollow cube of edge length 13
• 867 = 3 × 172, number of 5-chromatic simple graphs on 8 nodes[60]
• 868 = 22 × 7 × 31 = J3(10),[61] nontotient
• 869 = 11 × 79, the Mertens function of 869 returns 0

### 870s

• 870 = 2 × 3 × 5 × 29, sum of ten consecutive primes (67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), pronic number,[12] nontotient, sparsely totient number,[34] Harshad number
• 871 = 13 × 67, thirteenth tridecagonal number
• 872 = 23 × 109, refactorable number, nontotient, 872! + 1 is prime
• 873 = 32 × 97, sum of the first six factorials from 1
• 874 = 2 × 19 × 23, sphenic number, sum of the first twenty-three primes, sum of the first seven factorials from 0, nontotient, Harshad number, happy number
• 875 = 53 × 7, unique expression as difference of positive cubes:[62] 103 - 53
• 876 = 22 × 3 × 73, generalized pentagonal number[63]
• 877 = prime number, Bell number,[64] Chen prime, the Mertens function of 877 returns 0, strictly non-palindromic number,[23] prime index prime
• 878 = 2 × 439, nontotient, number of Pythagorean triples with hypotenuse < 1000.[65]
• 879 = 3 × 293, number of regular hypergraphs spanning 4 vertices,[66] candidate Lychrel seed number

### 880s

• 880 = 24 × 5 × 11 = 11!!!,[67] Harshad number; 148-gonal number; the number of n×n magic squares for n = 4.
• country calling code for Bangladesh
• 881 = prime number, twin prime, sum of nine consecutive primes (79 + 83 + 89 + 97 + 101 + 103 + 107 + 109 + 113), Chen prime, Eisenstein prime with no imaginary part, happy number
• 882 = 2 × 32 × 72 = ${\displaystyle {\binom {9}{5}}_{2}}$  a trinomial coefficient,[68] Harshad number, totient sum for first 53 integers, area of a square with diagonal 42[1]
• 883 = prime number, twin prime, sum of three consecutive primes (283 + 293 + 307), the Mertens function of 883 returns 0
• 884 = 22 × 13 × 17, the Mertens function of 884 returns 0, number of points on surface of tetrahedron with sidelength 21[69]
• 885 = 3 × 5 × 59, sphenic number, number of series-reduced rooted trees whose leaves are integer partitions whose multiset union is an integer partition of 7.[70]
• 886 = 2 × 443, the Mertens function of 886 returns 0
• country calling code for Taiwan
• 887 = prime number followed by primal gap of 20, safe prime,[31] Chen prime, Eisenstein prime with no imaginary part
• 888 = 23 × 3 × 37, sum of eight consecutive primes (97 + 101 + 103 + 107 + 109 + 113 + 127 + 131), Harshad number, strobogrammatic number,[9] happy number, 888!! - 1 is prime[71]
• 889 = 7 × 127, the Mertens function of 889 returns 0

### 890s

• 890 = 2 × 5 × 89 = 192 + 232 (sum of squares of two successive primes),[72] sphenic number, sum of four consecutive primes (211 + 223 + 227 + 229), nontotient
• 891 = 34 × 11, sum of five consecutive primes (167 + 173 + 179 + 181 + 191), octahedral number
• 892 = 22 × 223, nontotient, number of regions formed by drawing the line segments connecting any two perimeter points of a 6 times 2 grid of squares like this (sequence A331452 in the OEIS).
• 893 = 19 × 47, the Mertens function of 893 returns 0
• Considered an unlucky number in Japan, because its digits read sequentially are the literal translation of yakuza.
• 894 = 2 × 3 × 149, sphenic number, nontotient
• 895 = 5 × 179, Smith number,[21] Woodall number,[73] the Mertens function of 895 returns 0
• 896 = 27 × 7, refactorable number, sum of six consecutive primes (137 + 139 + 149 + 151 + 157 + 163), the Mertens function of 896 returns 0
• 897 = 3 × 13 × 23, sphenic number, cullen number (sequence A002064 in the OEIS)
• 898 = 2 × 449, the Mertens function of 898 returns 0, nontotient
• 899 = 29 × 31 (a twin prime product),[74] happy number, smallest number with digitsum 26,[75] number of partitions of 51 into prime parts

## References

1. ^ a b Sloane, N. J. A. (ed.). "Sequence A001105". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
2. ^ (sequence A229093 in the OEIS)
3. ^ (sequence A005893 in the OEIS)
4. ^ Sloane, N. J. A. (ed.). "Sequence A003107 (Number of partitions of n into Fibonacci parts (with a single type of 1))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
5. ^ "804 refactorable - OEIS". oeis.org. Retrieved 2022-12-20.
6. ^ Sloane, N. J. A. (ed.). "Sequence A002095 (Number of partitions of n into nonprime parts)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
7. ^ Sloane, N. J. A. (ed.). "Sequence A002088". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
8. ^ Sloane, N. J. A. (ed.). "Sequence A024816 (Antisigma(n): Sum of the numbers less than n that do not divide n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
9. ^ a b c Sloane, N. J. A. (ed.). "Sequence A000787 (Strobogrammatic numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
10. ^ Sloane, N. J. A. (ed.). "Sequence A005384 (Sophie Germain primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
11. ^ Sloane, N. J. A. (ed.). "Sequence A154638 (a(n) is the number of distinct reduced words of length n in the Coxeter group of "Apollonian reflections" in three dimensions)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
12. ^ a b Sloane, N. J. A. (ed.). "Sequence A002378 (Oblong (or promic, pronic, or heteromecic) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
13. ^
14. ^ Sloane, N. J. A. (ed.). "Sequence A049312 (Number of graphs with a distinguished bipartite block, by number of vertices)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
15. ^ Sloane, N. J. A. (ed.). "Sequence A000292 (Tetrahedral numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
16. ^ Sloane, N. J. A. (ed.). "Sequence A000931 (Padovan sequence)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
17. ^ Sloane, N. J. A. (ed.). "Sequence A003215 (Hex (or centered hexagonal) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
18. ^ Sloane, N. J. A. (ed.). "Sequence A000330 (Square pyramidal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
19. ^ a b Sloane, N. J. A. (ed.). "Sequence A000217 (Triangular numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
20. ^ Sloane, N. J. A. (ed.). "Sequence A005282 (Mian-Chowla sequence)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
21. ^ a b c d Sloane, N. J. A. (ed.). "Sequence A006753 (Smith numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
22. ^ Sloane, N. J. A. (ed.). "Sequence A098859 (Number of partitions of n into parts each of which is used a different number of times)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
23. ^ a b Sloane, N. J. A. (ed.). "Sequence A016038 (Strictly non-palindromic numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
24. ^ (sequence A045943 in the OEIS)
25. ^ Sloane, N. J. A. (ed.). "Sequence A001401 (Number of partitions of n into at most 5 parts)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-25.
26. ^ (sequence A085449 in the OEIS)
27. ^ Sloane, N. J. A. (ed.). "Sequence A001845 (Centered octahedral numbers (crystal ball sequence for cubic lattice))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-06-02.
28. ^ Sloane, N. J. A. (ed.). "Sequence A001006 (Motzkin numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
29. ^ Sloane, N. J. A. (ed.). "Sequence A085787". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-30.
30. ^ Sloane, N. J. A. (ed.). "Sequence A027430". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
31. ^ a b c Sloane, N. J. A. (ed.). "Sequence A005385 (Safe primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
32. ^ Sloane, N. J. A. (ed.). "Sequence A100827 (Highly cototient numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
33. ^ Sloane, N. J. A. (ed.). "Sequence A002182 (Highly composite numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
34. ^ a b Sloane, N. J. A. (ed.). "Sequence A036913 (Sparsely totient numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
35. ^
36. ^ Sloane, N. J. A. (ed.). "Sequence A001844 (Centered square numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
37. ^ Sloane, N. J. A. (ed.). "Sequence A069099 (Centered heptagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
38. ^ Sloane, N. J. A. (ed.). "Sequence A016754 (Odd squares: a(n) = (2n+1)^2. Also centered octagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
39. ^ Sloane, N. J. A. (ed.). "Sequence A007749 (Numbers k such that k!! - 1 is prime)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
40. ^ Sloane, N. J. A. (ed.). "Sequence A000014 (Number of series-reduced trees with n nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
41. ^ Sloane, N. J. A. (ed.). "Sequence A000032 (Lucas numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
42. ^ Sloane, N. J. A. (ed.). "Sequence A045882 (Smallest term of first run of (at least) n consecutive integers which are not squarefree)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
43. ^ Sloane, N. J. A. (ed.). "Sequence A032527 (Concentric pentagonal numbers: floor( 5*n^2 / 4 ))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
44. ^ Sloane, N. J. A. (ed.). "Sequence A182699 (Number of emergent parts in all partitions of n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
45. ^ Sloane, N. J. A. (ed.). "Sequence A002865 (Number of partitions of n that do not contain 1 as a part)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
46. ^ Sloane, N. J. A. (ed.). "Sequence A032020 (Number of compositions (ordered partitions) of n into distinct parts)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
47. ^ Sloane, N. J. A. (ed.). "Sequence A000326 (Pentagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
48. ^ Sloane, N. J. A. (ed.). "Sequence A001608 (Perrin sequence)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
49. ^ Sloane, N. J. A. (ed.). "Sequence A002995 (Number of unlabeled planar trees (also called plane trees) with n nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
50. ^ Sloane, N. J. A. (ed.). "Sequence A001107 (10-gonal (or decagonal) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
51. ^ Sloane, N. J. A. (ed.). "Sequence A005898 (Centered cube numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
52. ^ Sloane, N. J. A. (ed.). "Sequence A001106 (9-gonal (or enneagonal or nonagonal) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
53. ^ Sloane, N. J. A. (ed.). "Sequence A005891 (Centered pentagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
54. ^ Sloane, N. J. A. (ed.). "Sequence A007850 (Giuga numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
55. ^ Sloane, N. J. A. (ed.). "Sequence A000219 (Number of planar partitions (or plane partitions) of n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
56. ^ Sloane, N. J. A. (ed.). "Sequence A019506 (Hoax numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
57. ^ Sloane, N. J. A. (ed.). "Sequence A000384 (Hexagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
58. ^ Sloane, N. J. A. (ed.). "Sequence A001606 (Indices of prime Lucas numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
59. ^ Sloane, N. J. A. (ed.). "Sequence A006534". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-10.
60. ^ Sloane, N. J. A. (ed.). "Sequence A076281 (Number of 5-chromatic (i.e., chromatic number equals 5) simple graphs on n nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
61. ^ Sloane, N. J. A. (ed.). "Sequence A059376 (Jordan function J_3(n))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
62. ^ Sloane, N. J. A. (ed.). "Sequence A014439 (Differences between two positive cubes in exactly 1 way.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2019-08-18.
63. ^ Sloane, N. J. A. (ed.). "Sequence A001318 (Generalized pentagonal numbers.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2019-08-26.
64. ^ Sloane, N. J. A. (ed.). "Sequence A000110 (Bell or exponential numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
65. ^ Sloane, N. J. A. (ed.). "Sequence A101929 (Number of Pythagorean triples with hypotenuse < 10^n.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.
66. ^ Sloane, N. J. A. (ed.). "Sequence A319190 (Number of regular hypergraphs)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2019-08-18.
67. ^ Sloane, N. J. A. (ed.). "Sequence A007661 (Triple factorial numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.
68. ^ Sloane, N. J. A. (ed.). "Sequence A111808 (Left half of trinomial triangle (A027907), triangle read by rows)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.
69. ^ Sloane, N. J. A. (ed.). "Sequence A005893 (Number of points on surface of tetrahedron)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.
70. ^ Sloane, N. J. A. (ed.). "Sequence A319312 (Number of series-reduced rooted trees whose leaves are integer partitions whose multiset union is an integer partition of n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.
71. ^ Sloane, N. J. A. (ed.). "Sequence A007749 (Numbers k such that k!! - 1 is prime)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-24.
72. ^ Sloane, N. J. A. (ed.). "Sequence A069484 (a(n) = prime(n+1)^2 + prime(n)^2.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.
73. ^ Sloane, N. J. A. (ed.). "Sequence A003261 (Woodall numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-11.
74. ^ Sloane, N. J. A. (ed.). "Sequence A037074 (Numbers that are the product of a pair of twin primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.
75. ^ Sloane, N. J. A. (ed.). "Sequence A051885 (Smallest number whose sum of digits is n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-11.