Prove that IMO Longlist 1989 is periodic
Source: IMO Longlist 1989, Problem 15
September 18, 2008
functionalgebrarational functionalgebra unsolved
Problem Statement
A sequence is defined recursively by a_1 \equal{} 1 and a_{2^k\plus{}j} \equal{} \minus{}a_j (j \equal{} 1, 2, \ldots, 2^k). Prove that this sequence is not periodic.