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Strong numbers

Source: Indonesian Mathematical Olympiad 2013 Problem 6

September 5, 2013
quadraticsnumber theory unsolvednumber theory

Problem Statement

A positive integer nn is called "strong" if there exists a positive integer xx such that xnx+1x^{nx} + 1 is divisible by 2n2^n.
a. Prove that 20132013 is strong. b. If mm is strong, determine the smallest yy (in terms of mm) such that ymy+1y^{my} + 1 is divisible by 2m2^m.