proposition: Lemma Mi_rec i j: Mi i.+1 j.+1 = Mi i j + (Mi i j.+1).*2 + Mi i j.+2.
proof: Proof. exact. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype) mathcomp(ssrnat seq path div) mathcomp(fintype tuple finfun bigop finset binomial)