proposition: Lemma raddfMn n : {morph f : x / x *+ n}.
proof: Proof. by elim: n => [|n IHn] x /=; rewrite ?raddf0 // !mulrS raddfD IHn. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)