fact: Fixpoint nat_ns (p : Z)(n : nat) := match n with |0 => [:: p] |m.+1 => (p - (Z_of_nat m.+1))%Z :: nat_ns p m end.
imports: ZArith Zwf Lia mathcomp(ssreflect eqtype ssrbool ssrnat div fintype seq ssrfun order) mathcomp(bigop fingroup choice ssralg ssrnum rat poly) pol