proposition: Lemma p_eltX pi x n : pi.-elt x -> pi.-elt (x ^+ n).
proof: Proof. by rewrite -{1}[x]expg1 !p_elt_exp dvdn1 => /eqnP->. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(fintype bigop finset prime fingroup morphism) mathcomp(gfunctor automorphism quotient action gproduct) mathcomp(cyclic)