(** Multiply all elements except first occurance of x *)

Definition zmultDrop (x : Z) (l : Zlist) := zproduct (zdrop x l).

Lemma multdropzmultdrop : forall (q : nat) (qlist : natlist), Z_of_nat (multDrop q qlist) = zmultDrop (Z_of_nat q) (map nat Z Z_of_nat qlist).