proposition: Lemma mulmxnE A d i j : (A *+ d) i j = A i j *+ d.
proof: Proof. by elim: d => [|d IHd]; rewrite ?mulrS mxE ?IHd. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)