MathDB
Putnam 2003 A6

Source:

June 23, 2011
Putnamcollege contestspartitioncombinatoricsgenerating functions

Problem Statement

For a set SS of nonnegative integers, let rS(n)r_S(n) denote the number of ordered pairs (s1,s2)(s_1, s_2) such that s1Ss_1 \in S, s2Ss_2 \in S, s1s2s_1 \neq s_2, and s1+s2=ns_1 + s_2 = n. Is it possible to partition the nonnegative integers into two sets AA and BB in such a way that rA(n)=rB(n)r_A(n) = r_B(n) for all nn?