A154932 Decimal expansion of Sum_{q in A006881} 1/(q(q-1)) over the squarefree semiprimes q.

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

Offset: 0

Author

R. J. Mathar, Jan 17 2009

Keywords

• cons
• nonn
• more

Comments

A variant of A152447.

Examples

			Equals 0.071606015364062950... = 1/(6*5) + 1/(10*9) + 1/(14*13) + 1/(15*14) + ...
		

Links

• R. J. Mathar, Series of reciprocal powers of k-almost primes, arXiv:0803.0900 [math.NT], 2008-2009; see Table 9.

Formula

Equals Sum_{j>=1} 1/(A006881(j)*(A006881(j)-1)) = A152447 - Sum_{p in A000040} 1/(p^2*(p^2-1)) = A152447 + A085548 - Sum_{p in A000040} 1/(p^2-1).