proposition: Lemma natrX n k : (n ^ k)%:R = n%:R ^+ k :> R.
proof: Proof. by rewrite exprMn_n expr1n. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)