theorem le_B_split1_teta:\forall n.18 \le n \to not_bertrand n \to
B_split1 (2*n) \le teta (2 * n / 3).
-intros.unfold B_split1.unfold teta.
+intros. unfold B_split1.unfold teta.
apply (trans_le ? (pi_p (S (2*n)) primeb (λp:nat.(p)\sup(bool_to_nat (eqb (k (2*n) p) 1)))))
[apply le_pi_p.intros.
apply le_exp