Description: Lemma for chebbnd1 : show a lower bound on ppi ( x ) at even integers using similar techniques to those used to prove bpos . (Note that the expression K is actually equal to 2 x. N , but proving that is not necessary for the proof, and it's too much work.) The key to the proof is bposlem1 , which shows that each term in the expansion ( ( 2 x. N )C N ) = prod p e. Prime ( p ^ ( p pCnt ( ( 2 x. N )C N ) ) ) is at most 2 x. N , so that the sum really only has nonzero elements up to 2 x. N , and since each term is at most 2 x. N , after taking logs we get the inequality ppi ( 2 x. N ) x. log ( 2 x. N ) < log ( ( 2 x. N ) _C N ) , and bclbnd finishes the proof. (Contributed by Mario Carneiro, 22-Sep-2014) (Revised by Mario Carneiro, 15-Apr-2016)
Ref | Expression | ||
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Hypothesis | chebbnd1lem1.1 | |
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Assertion | chebbnd1lem1 | |