fact: Fixpoint intpartnsk_nb sm sz mx : nat := if sz is sz.+1 then iteri (minn sm mx) (fun i n => n + intpartnsk_nb (sm - i.+1) sz i.+1) 0 else if sm is sm.+1 then 0 else 1.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype