n^{n-1}-m^{m-1} is not divisible by k
Source: MEMO 2009, problem 4, single competition
October 1, 2009
quadraticsmodular arithmeticnumber theorynumber theory proposed
Problem Statement
Determine all integers such that for all pairs , of different positive integers not greater than , the number n^{n\minus{}1}\minus{}m^{m\minus{}1} is not divisible by .