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Turkish MO 1995 P5

Source: Turkish Mathematical Olympiad 2nd Round 1995

September 30, 2006
inductioncombinatorics unsolvedcombinatorics

Problem Statement

Let t(A)t(A) denote the sum of elements of a nonempty set AA of integers, and define t()=0t(\emptyset)=0. Find a set XX of positive integers such that for every integers kk there is a unique ordered pair of disjoint subsets (Ak,Bk)(A_{k},B_{k}) of XX such that t(Ak)t(Bk)=kt(A_{k})-t(B_{k}) = k.