Wikipedia:Reference desk/Archives/Mathematics/2023 June 8

Welcome to the Wikipedia Mathematics Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

June 8

186 as a typo for 286 in Pascal's triangle

The correct value of $13 \choose 3$ and $13 \choose 10$ is 286. But I noticed that many images of Pascal's triangle on the web (e.g., the ones at http://jwilson.coe.uga.edu/EMAT6680Su12/Berryman/6690/BerrymanK-Pascals/BerrymanK-Pascals.html, https://fractalfoundation.org/resources/fractivities/pascals-sierpinski-triangle/, and https://ptri1.tripod.com/) show 186 instead, which is a typo for 286.

So, why does the typo 186 appear in those images when it should correctly be 286? GeoffreyT2000 (talk) 16:40, 8 June 2023 (UTC)

You are right – looking at it in any of then it's obviously wrong as it's not bigger than both the numbers above that are added to produce it. You would have to take it up with those web sites to find out exactly why, but I would guess a typo then copying from each other or another source. A good reason to avoid those web sites – if they can make such a basic and obvious error what else will they have gotten wrong? 92.41.105.60 (talk) 16:47, 8 June 2023 (UTC)

And for the record, the important sites such as OEIS, have the number 286 correctly: https://oeis.org/A007318/b007318.txt Dhrm77 (talk) 19:38, 8 June 2023 (UTC)

I'm guessing that the numbers were all copied and pasted from a single location with the original error. That seems unnecessary since it's easy enough to compute the values yourself in a spreadsheet. The J. Wilson site has a contact email where you can at least try to notify someone about the error. I didn't see emails on the other sites, but I didn't look that hard either. --RDBury (talk) 23:24, 8 June 2023 (UTC)

These were just three examples from a multitude of pages with this specific error, which has also appeared in print. I suspect that this is the original sinner.  --Lambiam 07:44, 9 June 2023 (UTC)