proposition: Lemma val_intpartn2 (sh : 'P_2) : sh = [:: 2] :> seq nat \/ sh = [:: 1; 1] :> seq nat.
proof: Proof. case: sh => sh Hsh /=; move: Hsh; rewrite enum_partnP. by rewrite /enum_partn /= !inE => /orP[] /eqP ->; [left | right]. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype