N5 Indonesian 2014 Shortlist
Source: Shortlist OSN Indonesia 2014, N5
May 13, 2017
number theorypigeonhole principlenational olympiad
Problem Statement
Prove that we can give a color to each of the numbers with seven distinct colors (all colors are necessarily used) such that for any distinct numbers of the same color, then and the remainder when is divided by is of the same color as .