(* We now define the recurrence relation *)

Inductive CR: nat -> R -> Prop :=
  | C0: CR 0 0
  | Cn n (l: list R): elemsR CR (nats 0 (S n)) l -> CR (S n) (n + 2 * Ravg l).(* We now define the recurrence relation *)

Inductive CR: nat -> R -> Prop :=
  | C0: CR 0 0
  | Cn n (l: list R): elemsR CR (nats 0 (S n)) l -> CR (S n) (n + 2 * Ravg l).(* We now define the recurrence relation *)

Inductive CR: nat -> R -> Prop :=
  | C0: CR 0 0
  | Cn n (l: list R): elemsR CR (nats 0 (S n)) l -> CR (S n) (n + 2 * Ravg l).

Lemma CRimpl: forall n (a: Acc lt n), sig (CR n).