MathDB
Problem in 1995 Bulgaria MO (Number Theory)

Source:

December 9, 2015
number theory

Problem Statement

Suppose that xx and yy are different real numbers such that xnynxy\frac{x^n-y^n}{x-y} is an integer for some four consecutive positive integers nn. Prove that xnynxy\frac{x^n-y^n}{x-y} is an integer for all positive integers n.