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I know that there is a result from J Wu that the number of twin primes less than a given magnitude $N$ does not exceed $$\frac{2aCN}{\log^2{N}}$$ Where $C=\prod \frac{p(p-2)}{(p-1)^2}$ and $a$ is something like $3.4$. Is this a direct result of the Selberg Sieve, or is there additional knowledge on the distribution of Twin Primes used?


marked as duplicate by Gerry Myerson, Andrés E. Caicedo, Andrey Rekalo, Willie Wong, David Roberts Jul 9 '13 at 9:46

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