proposition: Lemma exprSr x n : x ^+ n.+1 = x ^+ n * x.
proof: Proof. by rewrite -addn1 exprD expr1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)