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.

The sum of the first n terms of a geometric series is:

S_n = t₁(1-r^n)/(1-r)

where t₁ is the first term and r is the common ratio (and not 0).

Since this problem specifies that t₁=1, we need to find a solution for

S_n = (1-r^n)/(1-r) = x²

where x, r, and n are all integers.

I haven't time to complete it now (back to work!), but that is where I think we need to start.

Posted by DJ on 2003-07-14 06:43:22