IMO 2015 Shortlist N1
Determine all positive integers M for which the sequence a0,a1,a2,..., defined by a0 “ 2M1 and ak1 “ aktaku for k “ 0,1,...
Category: Number Theory
Problem
Determine all positive integers M for which the sequence a0,a1,a2,..., defined by
a0 “ 2M1 and ak1 “ aktaku for k “ 0,1,2,..., contains at least one integer term.
(Luxembourg)