proposition: Lemma coprimeDr m n: coprime m (n + m) = coprime m n.
proof: Proof. by rewrite/coprime gcdnDr. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)