Find all sets of four natural numbers such that the square of each of them, when added to the sum of the other three, again yields a perfect square.
(In reply to
Is there a pattern to this? by brianjn)
For the sets that contain a 1, the pattern apparently is that any (q^21)/3 that is an integer (two out of every three are) will work as the other three.
The problem is indeed those erratic ones that don't contain a 1.

Posted by Charlie
on 20081212 11:18:18 