MathDB
Putnam 2005 B4

Source:

December 5, 2005
Putnamfunctioninductioncalculusintegrationcollege contests

Problem Statement

For positive integers m m and n n, let f(m,n) f\left(m,n\right) denote the number of n n-tuples (x1,x2,,xn) \left(x_1,x_2,\dots,x_n\right) of integers such that \left|x_1\right| \plus{} \left|x_2\right| \plus{} \cdots \plus{} \left|x_n\right|\le m. Show that f\left(m,n\right) \equal{} f\left(n,m\right).