MathDB
find A with largest possible cardinality

Source: China Team Selection Test 2003, Day 1, Problem 2

October 13, 2005
quadraticsmodular arithmeticcombinatorics unsolvedcombinatorics

Problem Statement

Suppose A⊆{0,1,…,29}A\subseteq \{0,1,\dots,29\}. It satisfies that for any integer kk and any two members a,b∈Aa,b\in A(a,ba,b is allowed to be same), a+b+30ka+b+30k is always not the product of two consecutive integers. Please find AA with largest possible cardinality.
Back to ProblemsView on AoPS