fact: Definition PS_derive_n (n : nat) (a : nat -> R) := (fun k => (INR (fact (k + n)%nat) / INR (fact k)) * a (k + n)%nat).
imports: Coq(Reals Psatz ssreflect) Rcomplements Rbar Lim_seq Lub Hierarchy Continuity Derive Seq_fct Series