proposition: Lemma lead_coef_exp p n : lead_coef (p ^+ n) = lead_coef p ^+ n.
proof: Proof. elim: n => [|n IHn]; first by rewrite !expr0 lead_coef1. by rewrite !exprS lead_coefM IHn. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)