MathDB
A1,...an

Source: 17-th Iranian Mathematical Olympiad 1999/2000

December 14, 2005
algebrapolynomialalgebra proposed

Problem Statement

Let nn be a positive integer. Suppose SS is a set of ordered n-\mbox{tuples} of nonnegative integers such that, whenever (a1,,an)S(a_1,\dots,an)\in S and bib_i are nonnegative integers withbiaib_i\le a_i, the ntuplen-\text{tuple} (b1,,bn)(b_1,\dots,b_n) is also in SS. If hmh_m is the number of elements of SS with the sum of components equal tomm, prove that hmh_m is a polynomial in mm for all sufficiently largemm.