proposition: Lemma pascal11 n: \sum_(i < n.+1) 'C(n, i) = 2 ^ n.
proof: Proof. by rewrite (Pascal 1 1 n); apply: eq_bigr => i _ //; rewrite !exp1n !muln1. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype) mathcomp(ssrnat seq path div) mathcomp(fintype tuple finfun bigop finset binomial)