Re: [math-fun] Number of ways to pick 4 points from an m X n grid?

On 14/06/2020 22:22, Tom Duff wrote:

Here's my table up to 21x21 using the stupidest possible program, which just enumerates and classifies each set of 4 points. 21x21 because that's where 32 bit counters start to overflow. I'm rerunning with 64 bit counters (up to 331x331), but someone will find good recurrences before it even gets close to finishing. Of course, the chance that my program has exactly zero bugs is not large.

In particular, it is at most 1. :-) -- g