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.

A194506 Denominator of the third row of the inverse Akiyama-Tanigawa algorithm from 1/n.

Original entry on oeis.org

3, 12, 120, 360, 1008, 20160, 259200, 907200, 6652800, 19160064, 39626496000, 62270208000, 603542016000, 640493568000, 1067062284288000, 4001483566080000, 4174096582656000, 162193467211776000, 13651830701752320000, 481714597618974720000
Offset: 0

Views

Author

Paul Curtz, Aug 27 2011

Keywords

Comments

For the numerator sequence and detailed information see A193546.

Crossrefs

Cf. A193546 (numerator).

Programs

  • Mathematica
    a[n_, 0] := 1/(n+1); a[n_, m_] := a[n, m] = a[n, m-1] - a[n+1, m-1]/m; a[n_] := a[2, n]; Table[a[n] , {n, 0, 19}] // Denominator (* Jean-François Alcover, Sep 18 2012 *)
    Numerator@Table[(-1)^n (n + 1) Integrate[FunctionExpand[x Binomial[x, n + 1]], {x, 0, 1}], {n, 0, 20}] (* Vladimir Reshetnikov, Feb 01 2017 *)

Formula

a(n)/A194506(n) = (-1)^n * (n+1) * Integral_{x=0..1} x*binomial(x,n+1). - Vladimir Reshetnikov, Feb 01 2017

A321943 Decimal expansion of Ni_1 = (1/2)*(gamma - log(2*Pi)) + 1, where gamma is Euler's constant (or the Euler-Mascheroni constant).

Original entry on oeis.org

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

Views

Author

Stefano Spezia, Dec 12 2018

Keywords

Comments

This constant links Euler's constant and Pi to the values of the Riemann zeta function at positive integers (see formulas).

Examples

			0.369669299246093688522926308635583575659682194332178386585...
		

References

  • D. Suryanarayana, Sums of Riemann zeta function, Math. Student, 42 (1974), 141-143.

Crossrefs

Cf. A001620 (Euler's constant), A000796 (Pi).

Programs

  • Maple
    Digits := 100; evalf((1/2)*(gamma-ln(2*Pi))+1);
  • Mathematica
    First[RealDigits[N[(1/2)*(EulerGamma-Log[2*Pi])+1, 100], 10]]
  • PARI
    (1/2)*(Euler-log(2*Pi))+1
    
  • Python
    from mpmath import *
    mp.dps = 100; mp.pretty = True
    +(1/2)*(euler-log(2*pi))+1

Formula

Ni_1 = Sum_{k>=2} (-1)^k*zeta(k)/(k+1).
Ni_1 = Sum_{n>0} (Integral_{x=0..1} x^2*(1-x)_{n-1} dx)/(n*n!), where (z)_n = z*(z+1)*(z+2)*...*(z+n-1) is the Pochhammer symbol.
Ni_1 = Sum_{n>=0} A193546(n)/(A000290(n + 1)*A194506(n)).

A232853 Repeat n+1 times A091137(n).

Original entry on oeis.org

1, 2, 2, 12, 12, 12, 24, 24, 24, 24, 720, 720, 720, 720, 720, 1440, 1440, 1440, 1440, 1440, 1440, 60480, 60480, 60480, 60480, 60480, 60480, 60480, 120960, 120960, 120960, 120960, 120960, 120960, 120960, 120960, 3628800
Offset: 0

Views

Author

Paul Curtz, Dec 01 2013

Keywords

Comments

A002657(n) and A091137(n) are linked to the Bernoulli numbers B n.
Unreduced differences table of A002657(n)/A091137(n):
1, 1/2, 5/12, 9/24, 251/720, 475/1440,...
-1/2, -1/12, -1/24, -19/720, -27/1440,... =-A141417(n+1)/A091137(n+1),
5/12, 1/24, 11/720, 11/1440,...
-9/24, -19/720, -11/1440,...
251/720, 27/1440,...
-475/1440,... etc.
This is an autosequence of the second kind: its inverse binomial transform is the signed sequence with the main diagonal double of the first upper diagonal.
a(n) is the denominators written by antidiagonals.

Examples

			1,
2,   2,
12, 12, 12,
24, 24, 24, 24, etc.
		

References

  • P. Curtz, Intégration numérique des systèmes différentiels à conditions initiales. Centre de Calcul Scientifique de l'Armement, Arcueil 1969. Pages 36 and 56.

Crossrefs

Cf. A195287, A002208/A002209 (reduced autosequence), A193546, A174727, A165313.

Formula

Repeat n+1 times A091137(n). Triangle.
Showing 1-3 of 3 results.