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0,2

Geoffrey Landis and Jonathan Vos Post (personal communication) show that this constant equals ((P2)^2 + P4)/2, where P2 and P4 are constants in A085548 and A085964, respectively.

Table of n, a(n) for n=0..101.

Richard J. Mathar, Series of Reciprocal Powers of k-almost Primes, Table 4.

Eric Weisstein's World of Mathematics, Math World: Prime Zeta Function

0.14076043434902338822275... = 1/4^2 + 1/6^2 + 1/9^2 + 1/10^2 + 1/14^2 +1/15^2 +...

Cf. A001358 (semiprimes), A154928 (derivative).

A131653 (squared triprimes) [From T. D. Noe, Oct 09 2008]

Sequence in context: A272876 A133930 A077892 * A242970 A070433 A169821

Adjacent sequences: A117540 A117541 A117542 * A117544 A117545 A117546

cons,nonn

T. D. Noe, Mar 28 2006

approved