Definition maj_Reste_E (x y:R) (N:nat) : R :=
4 *
(Rmax 1 (Rmax (Rabs x) (Rabs y)) ^ (2 * N) /
Rsqr (INR (fact (Nat.div2 (pred N))))).

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Lemma div2_double : forall N:nat, Nat.div2 (2 * N) = N.