proposition: Lemma expn2S n: 2^n.+1 = (2^n).*2.
proof: Proof. by rewrite expnS mul2n. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)