A155799 - OEIS

A155799

Decimal expansion of the product_{q=3-almost-primes} (q^2-1)/(q^2+1).

9, 2, 5, 8, 5, 7, 2, 7, 4, 7, 1, 2, 8, 9, 3, 1, 2, 7, 9, 9, 8, 8, 8, 2, 1, 3, 8, 2, 0, 7, 1, 5, 8, 4, 1, 5, 2, 7, 8, 4, 5, 0, 2, 1, 8, 1, 9, 1, 9, 6, 6, 0, 2, 1, 5, 3, 2, 7, 6, 5, 6, 6, 2, 0, 2, 9, 5, 6, 7, 4, 4, 6, 8, 1, 0, 7, 1, 2, 4, 7, 5, 7, 0, 3, 9, 6, 4, 4, 8, 6, 6, 8, 9

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

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.

LINKS

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]

FORMULA

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

EXAMPLE

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

CROSSREFS

Cf. A112407.

Sequence in context: A326924 A328908 A275967 * A021112 A353407 A248318

Adjacent sequences: A155796 A155797 A155798 * A155800 A155801 A155802

KEYWORD

cons,nonn

AUTHOR

R. J. Mathar, Jan 27 2009

STATUS

approved