This number is a prime.

+ Four of the first 5 values are primes, up through this one, of partial sums of number of inequivalent ways of choosing n squares from an n-by-n board, considering rotations and reflections to be the same. After these (3, 19, 271, 251429) there are no more through 20-by-20. [Post]

Printed from the PrimePages <primes.utm.edu> © G. L. Honaker and Chris K. Caldwell