Symmetric integers
Source: IMO Longlist 1989, Problem
September 18, 2008
functionalgebra unsolvedalgebra
Problem Statement
The integers with are defined by
c_{m,0} \equal{} 1 \forall m \geq 0, c_{0,n} \equal{} 1 \forall n \geq 0,
and
c_{m,n} \equal{} c_{m\minus{}1,n} \minus{} n \cdot c_{m\minus{}1,n\minus{}1} \forall m > 0, n > 0.
Prove that c_{m,n} \equal{} c_{n,m} \forall m > 0, n > 0.