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.

A269330 Decimal expansion of the "alternating Euler constant" beta = li(2) - gamma.

Original entry on oeis.org

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

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Author

Keywords

Comments

The function li(x) is the integral logarithm, gamma is Euler's constant.
Decimal expansion of Sum_{n>=1} G_n/n = beta, where numbers G_n are Gregory's coefficients (see A002206 and A002207). In comparison to the Fontana-Mascheroni's series Sum_{n>=1} |G_n|/n = gamma (see A195189), the constant beta may be regarded as the "alternating Euler constant". A similar analogy also exists between gamma and log(4/Pi), see A094640.
Another striking analogy between beta and gamma follows from the fact that beta = Integral_{x=0..1} (1/log(1+x) - 1/x) dx, while gamma = Integral_{x=0..1} (1/log(1-x) + 1/x) dx.
For more details, see references below.

Examples

			0.4679481152159599242380767991122107054804562422112779...
		

Crossrefs

Programs

  • Maple
    evalf(Li(2)-gamma, 120)
    evalf(Ei(ln(2))-gamma, 120)
    evalf(int(1/ln(1+x)-1/x, x = 0..1), 120)
    evalf(ln(ln(2))+sum(ln(2)^k/(k*factorial(k)), k = 1..infinity), 120)
  • Mathematica
    RealDigits[LogIntegral[2] - EulerGamma, 10, 120][[1]]
    RealDigits[ExpIntegralEi[Log[2]] - EulerGamma, 10, 120][[1]]
    RealDigits[Integrate[1/Log[1+x] - 1/x, {x, 0, 1}], 10, 120][[1]]
    RealDigits[Log[Log[2]] + Sum[Log[2]^k/(k*k!), {k, 1, ∞}], 10, 120][[1]]
  • PARI
    default(realprecision, 120); -real(eint1(-log(2)))-Euler
    
  • PARI
    default(realprecision, 120); intnum(x=0,1,1/log(1+x)-1/x) \\ Note: PARI/GP v. 2.7.3 is able to compute only 19 digits
    
  • PARI
    default(realprecision,120); log(log(2))+sumpos(k=1,log(2)^k/(k*factorial(k)))

Formula

Equals li(2) - gamma.
Equals Ei(log(2)) - gamma.
Equals Integral_{x=0..1} (1/log(1+x) - 1/x) dx.
Equals log(log(2)) + Sum_{k>=1} log(2)^k/(k*k!).

A069285 Continued fraction for Li(2).

Original entry on oeis.org

1, 22, 7, 16, 1, 1, 2, 1, 4, 6, 1, 40, 1, 1, 1, 1, 1, 1, 3, 9, 1, 1, 1, 1, 35, 7, 9, 2, 1, 3, 8, 2, 5, 1, 1, 4, 1, 1, 6, 1, 18, 14, 1, 10, 1, 3, 1, 1, 5, 4, 1, 59, 1, 7, 2, 1, 1, 7, 1, 43, 12, 21, 2, 4, 8, 16, 1, 22, 4, 37, 1, 1, 1, 12, 1, 1, 1, 3, 3, 1, 1, 1, 4, 1, 3, 5, 3, 1, 33, 2, 15, 5, 2
Offset: 0

Views

Author

Frank Ellermann, Mar 13 2002

Keywords

Examples

			1.0451637801174927848445888891946131365226155781512015758329...
		

Crossrefs

Cf. A069284 (decimal expansion).

Programs

  • Mathematica
    ContinuedFraction[LogIntegral[2],100] (* Harvey P. Dale, Dec 31 2015 *)
  • PARI
    contfrac(-real(eint1(-log(2)))) \\ G. C. Greubel, Apr 22 2018

Extensions

Offset changed by Andrew Howroyd, Aug 07 2024

A380270 Decimal expansion of Integral_{x=1..A070769} li(x) dx (negated), where li(x) is the logarithmic integral.

Original entry on oeis.org

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

Views

Author

Artur Jasinski, Jan 18 2025

Keywords

Comments

A070769 is Soldner's constant, where li(A070769)=0.
Integral_{x=0..1} li(x) dx = -log(2) then Integral_{x=0..A070769} li(x) dx = A380270 - log(2) = -1.19324951683011591582919049...

Examples

			-0.500102336270170606411958373..
		

Crossrefs

Programs

  • Mathematica
    y = x /. FindRoot[LogIntegral[x] == 0, {x, 1.5}, WorkingPrecision -> 200]; yy = -Integrate[LogIntegral[x], {x, 1, y}]; RealDigits[yy, 10, 105][[1]]
Showing 1-3 of 3 results.