MathDB

C2

Part of 2012 IMO Shortlist

Problems(1)

IMO Shortlist 2012, Combinatorics 2

Source: IMO Shortlist 2012, Combinatorics 2

7/29/2013
Let n≥1n \geq 1 be an integer. What is the maximum number of disjoint pairs of elements of the set {1,2,…,n}\{ 1,2,\ldots , n \} such that the sums of the different pairs are different integers not exceeding nn?
IMO ShortlistcombinatoricsExtremal combinatoricsDoublecounting