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.

There are an innumerable number of series that satisfy the given conditions.

Two these are 1,7,49,343 and 1,3,9,27,81.

Edited on November 9, 2007, 9:16 am

Posted by K Sengupta on 2007-11-08 09:53:58