A084892 Decimal expansion of Product_{j>=1, j!=2} zeta(j/2) (negated).

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

Offset

2,2

Comments

This constant, A_2, appears in the asymptotic formula A063966(n) = Sum_{k=1..n} A000688(k) = A_1 * n + A_2 * n^(1/2) + A_3 * n^(1/3) + O(n^(50/199 + e)), where e>0 is arbitrarily small, A_1 = A021002, and A_3 = A084893. - Amiram Eldar, Oct 16 2020

References

Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.1 Abelian group enumeration constants, p. 274.

Links

Table of n, a(n) for n=2..103.

B. R. Srinivasan, On the Number of Abelian Groups of a Given Order, Acta Arithmetica, Vol. 23, No. 2 (1973), pp. 195-205, alternative link.

Eric Weisstein's World of Mathematics, Abelian Group.

Example

-14.64756630163831131699976...

Mathematica

m0 = 100; dm = 100; digits = 102; Clear[p]; p[m_] := p[m] = Zeta[1/2]*Product[Zeta[j/2], {j, 3, m}]; p[m0]; p[m = m0 + dm]; While[RealDigits[p[m], 10, digits + 10] != RealDigits[p[m - dm], 10, digits + 10], Print["m = ", m]; m = m + dm]; RealDigits[p[m], 10, digits] // First (* Jean-François Alcover, Jun 23 2014 *)

Prog

(PARI) prodinf(k=1, if (k!=2, zeta(k/2), 1)) \\ Michel Marcus, Oct 16 2020

Crossrefs

Cf. A000688, A021002, A063966, A084893.

Sequence in context: A142973 A181110 A199959 * A344475 A245556 A256318

Adjacent sequences: A084889 A084890 A084891 * A084893 A084894 A084895

Keyword

nonn,cons

Author

Eric W. Weisstein, Jun 10 2003

Status

approved