proposition: Fact conj_intpartnP p : is_part_of_n n (conj_part p).
proof: Proof. Proof using. case: p => p /= /andP[/eqP <- Hpart]. by rewrite is_part_conj // sumn_conj_part /= eq_refl. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype