proposition: Lemma size_Xn_sub_1 n : n > 0 -> size ('X^n - 1 : {poly R}) = n.+1.
proof: Proof. by move=> n_gt0; rewrite size_addl size_polyXn // size_opp size_poly1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)