cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A021002 Decimal expansion of zeta(2)*zeta(3)*zeta(4)*...

Original entry on oeis.org

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

Views

Author

Andre Neumann Kauffman (ank(AT)nlink.com.br)

Keywords

Comments

A very good approximation is 2e-Pi = ~2.29497100332829723225793155942... - Marco Matosic, Nov 16 2005
This constant is equal to the asymptotic mean of number of Abelian groups of order n (A000688). - Amiram Eldar, Oct 16 2020

Examples

			2.2948565916733137941835158313443112887131637994416686732758140300...
		

References

  • R. Ayoub, An Introduction to the Analytic Theory of Numbers, Amer. Math. Soc., 1963, p. 198-9.
  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.1 Abelian group enumeration constants, p. 274.

Crossrefs

Cf. A068982 (reciprocal), A082868 (continued fraction).

Programs

  • Maple
    evalf(product(Zeta(n), n=2..infinity), 200);
  • Mathematica
    p = Product[ N[ Zeta[n], 256], {n, 2, 1000}]; RealDigits[p, 10, 111][[1]] (* Robert G. Wilson v, Nov 22 2005 *)
  • PARI
    prodinf(n=2,zeta(n)) \\ Charles R Greathouse IV, May 27 2015

Formula

Product of A080729 and A080730. - R. J. Mathar, Feb 16 2011

Extensions

More terms from Simon Plouffe, Jan 07 2002
Further terms from Robert G. Wilson v, Nov 22 2005
Mathematica program fixed by Vaclav Kotesovec, Sep 20 2014

A080729 Decimal expansion of the infinite product of zeta functions for even arguments.

Original entry on oeis.org

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

Views

Author

Deepak R. N (deepak_rn(AT)safe-mail.net), Mar 08 2003

Keywords

Comments

By elementary estimates, the constant lies in the open interval (Pi/6, exp(3/4)). - Bernd C. Kellner, May 18 2024

Examples

			1.82101745149929239040672513222600684857...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[Product[Zeta[2n],{n,500}],10,110][[1]] (* Harvey P. Dale, Jan 31 2012 *)
  • PARI
    prodinf(k=1, zeta(2*k)) \\ Vaclav Kotesovec, Jan 29 2024

Formula

Decimal expansion of zeta(2)*zeta(4)*...*zeta(2k)*...
If u(k) denotes the number of Abelian groups with group order k (A000688), then Product_{k>=1} zeta(2*k) = Sum_{k>=1} u(k)/k^2. - Benoit Cloitre, Jun 25 2003
Equals A021002/A080730. - Amiram Eldar, Jan 31 2024
This constant C is connected with the product of values of the Dedekind eta function on the upper imaginary axis. The product runs over the primes, where i is the imaginary unit: 1/C = Product_{prime p} (p^(1/12) * eta(i * log(p) / Pi)). - Bernd C. Kellner, May 18 2024

Extensions

More terms from Benoit Cloitre, Mar 08 2003

A355978 Decimal expansion of Product_{k>=1} zeta(Prime(k)).

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Jul 22 2022

Keywords

Examples

			2.06873599797165833786362198099404928341340749889767...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[Product[Zeta[Prime[n]], {n, 1, 100}], 10, 100][[1]]

Formula

Equals Product_{m,n>=1} 1/(1-prime(n)^(-prime(m))) = Product_{m>=1} 1/(1-1/A053810(m)).
Showing 1-3 of 3 results.