Find a geometric series of 3 or more positive integers, starting with 1, such that its sum is a perfect square.

See if you can find another such series.

If my program works correctly, my two solutions are the only ones resulting in a square smaller than 10,000,000, so it seems they are the only ones.
Maybe someone can find a proof that those are indeed the only solutions.

Posted by exoticorn on 2003-07-14 06:58:54