MathDB
2013 BMT Individual 11

Source:

January 18, 2022
combinatorics

Problem Statement

Let t=(a,b,c)t = (a, b, c), and let us define f1(t)=(a+b,b+c,c+a)f^1 (t) = (a + b, b + c, c + a) and fk(t)=fk1(f1(t))f^k (t) = f^{k-1}(f^1(t)) for all k>1k > 1. Furthermore, a permutation of tt has the same elements, just in a different order (e.g., (b,c,a)(b, c, a)). If f2013(s)f^{2013}(s) is a permutation of ss for some s=(k,m,n)s = (k, m, n), where k,mk, m, and nn are integers such that k,m,n10|k|, |m|, |n|\le 10, how many possible values of ss are there?