{75, 100, 125} is an example of an arithmetic progression of positive integers such that the n-th term is a perfect n-th power.
Find a longer sequence with this feature.

What is the longest you can get?
P.S. Trival solution(d=0) excluded.

It would seem to be simple to create a set of any length, e.g. by just finding any nth power, then working back by n-1 subtractions of 1 or any other constant.  e.g. (504,505,506,507,508,509,510,511,512) with 512=2**9.

Posted by ed bottemiller on 2010-07-22 14:40:13