MathDB
2013 PUMaC Combinatorics A3

Source:

November 23, 2013

Problem Statement

How many tuples of integers (a0,a1,a2,a3,a4)(a_0,a_1,a_2,a_3,a_4) are there, with 1ai51\leq a_i\leq 5 for each ii, so that a0<a1>a2<a3>a4a_0<a_1>a_2<a_3>a_4?