0,1

The 3-almost-prime analog of A112407. Its logarithm has been computed from -2*sum_{l=1..infinity} P_3(2*(2l-1))/(2l-1) where P_k(s) are the k-almost prime zeta functions of arXiv:0803.0900.

Table of n, a(n) for n=0..92.

R. J. Mathar, Series of reciprocal powers of k-almost primes, arXiv:0803.0900 [math.NT].

R. J. Mathar, Hardy-Littlewood constants embedded into infinite products over all positive integers, arXiv:0903.2514 [math.NT], third line Table 1. [From R. J. Mathar, Mar 28 2009]

product_{n=1..infinity} (A014612(n)^2-1)/(A014612(n)^2+1).

0.92585727... = 63/65*143/145*323/325*399/401*364/365*...

Cf. A112407.

Sequence in context: A326924 A328908 A275967 * A021112 A248318 A298852

Adjacent sequences: A155796 A155797 A155798 * A155800 A155801 A155802

cons,nonn

R. J. Mathar, Jan 27 2009

approved