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.

A158468 Decimal expansion of hz = limit_{k -> infinity} 1 + k - Sum_{j = -k..k} exp(-2^j).

Original entry on oeis.org

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

Views

Author

Alois P. Heinz, Mar 19 2009

Keywords

Comments

Curiously, this constant is close to gamma/log(2)+1/2 = 1.332746177... - Jean-François Alcover, Mar 24 2014

Examples

			1.3327473824328992250086010983738997044167439822598445365797...
		

Crossrefs

Cf. A100668 (gamma/log(2)), A158469 (continued fraction), A159835 (Engel expansion), A339168.

Programs

  • Maple
    hz:= limit(1+k -sum(exp(-2^j), j=-k..k), k=infinity):
    hzs:= convert(evalf(hz/10, 130), string):
    seq(parse(hzs[n+1]), n=1..120);
  • Mathematica
    digits = 105; Clear[f]; f[k_] := f[k] = 1 + k - Sum[Exp[-2^j], {j, -k, k}] // RealDigits[#, 10, digits+1]& // First // Quiet; f[1]; f[n=2]; While[f[n] != f[n-1], n++] ; f[n] // Most (* Jean-François Alcover, Feb 19 2013 *)

Formula

Equals gamma/log(2)+1/2 + Sum_{k>=1} Im(Gamma(1-2*k*Pi*i/log(2)))/(k*Pi). - Toshitaka Suzuki, Feb 10 2017
Also equals limit_{k->oo} 1 + Sum_{j>=1} 1-(1-1/2^j)^(2^k). - Toshitaka Suzuki, Feb 12 2017

A339168 Decimal expansion of Sum_{k>=1} Im(Gamma(1-2*k*Pi*i/log(2)))/(k*Pi).

Original entry on oeis.org

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

Views

Author

Alois P. Heinz, Nov 25 2020

Keywords

Examples

			0.00000120515603207436218357896578416925431245123351643494822...
		

Crossrefs

Programs

  • Maple
    evalf(sum(Im(GAMMA(1-2*k*Pi*I/log(2)))/(k*Pi), k=1..infinity), 120);

Formula

Equals A158468 - gamma/log(2) - 1/2.

A278326 Decimal expansion of gamma/log(2)^2.

Original entry on oeis.org

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

Views

Author

Alois P. Heinz, Nov 18 2016

Keywords

Examples

			1.2013987802765778241945150557561351168...
		

Crossrefs

Programs

  • Magma
    SetDefaultRealField(RealField(100)); R:= RealField(); EulerGamma(R)/Log(2)^2; // G. C. Greubel, Sep 05 2018
  • Mathematica
    RealDigits[EulerGamma/Log[2]^2,10,120][[1]] (* Harvey P. Dale, Dec 07 2017 *)
  • PARI
    Euler/log(2)^2 \\ Michel Marcus, Nov 19 2016
    

Formula

Equals -Integral_{x = -infinity..infinity} x*2^x*exp(-2^x) dx.
Showing 1-3 of 3 results.