proposition: Lemma stir1_nn n : 'So(n,n) = 1.
proof: Proof. by elim:n => // n Hr; rewrite stir1_S Hr stir1_small1 // muln0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype) mathcomp(ssrnat seq path div) mathcomp(fintype tuple finfun bigop finset binomial)