IMO 2008 Shortlist N2
Let a1,a2,...,an be distinct positive integers, n ≥ 3. Prove that there exist distinct indices i and j such that ai + aj...
Category: Number Theory
Problem
Let a1,a2,...,an be distinct positive integers, n ≥ 3. Prove that there exist distinct indices i and j such that ai + aj does not divide any of the numbers 3a1,3a2,...,3an.