fact: Definition Partition : forall n : nat, {f : nat -> nat | forall m : nat, 1 <= m /\ m <= 2 * n -> f m <> m /\ f (f m) = m /\ (1 <= f m /\ f m <= 2 * n) /\ prime (f m + m)}.
imports: Coq(Div2 Even Wf_nat Arith ArithRing List) Bertrand(Bertrand)