cannonball problem

It can be visualized as the problem of taking a square arrangement of cannonballs on the ground and building a square pyramid out of them.

cannonball problem

1. (mathematics) The challenge of proving that the only solution of the Diophantine equation :${\displaystyle \sum _{n=1}^{N}n^{2}=M^{2}\;}$ with N > 1 is when N = 24 and M = 70.