proposition: Lemma expg1n n : 1 ^+ n = 1 :> T.
proof: Proof. by elim: n => // n IHn; rewrite expgS mul1g. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)