IMO 2013 Shortlist N4
Determine whether there exists an infinite sequence of nonzero digits a1,a2,a3,... and a positive integer N such that fo...
Category: Number Theory
Problem
Determine whether there exists an infinite sequence of nonzero digits a1,a2,a3,... and a positive integer N such that for every integer k ą N, the number akak´1 ...a1 is a perfect square. (Iran)