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 1-4 of 4 results.

A285068 Denominators of the generalized Bernoulli numbers B[3,1] = 3^n*B(n, 1/3).

Original entry on oeis.org

1, 2, 2, 1, 10, 1, 14, 1, 10, 1, 22, 1, 910, 1, 2, 1, 170, 1, 266, 1, 110, 1, 46, 1, 910, 1, 2, 1, 290, 1, 4774, 1, 170, 1, 2, 1, 639730, 1, 2, 1, 4510, 1, 602, 1, 230, 1, 94, 1, 15470, 1, 22
Offset: 0

Views

Author

Wolfdieter Lang, Apr 28 2017

Keywords

Comments

The numerators are given in A157799.
Because B(n, 2/3) = (-1)^n*B(n, 1/3) (from the e.g.f. z*exp(x*z)/(exp(z)-1) of Bernoulli polynomials {B(n, x)}_{n>=0}) one has for the numbers B[3,2](n) = 3^n*B(n, 2/3) the numerators (-1)^n*A157799(n) and the denominators a(n).
This sequence gives also the denominators of {3^n*B(n)}_{n>=0} with numerators given in A285863.

Examples

			The Bernoulli numbers r(n) = B[3,1](n) begin: 1, -1/2, -1/2, 1, 13/10, -5, -121/14, 49, 1093/10, -809, -49205/22, 20317, 61203943/910, -722813, -5580127/2, 34607305, ...
The Bernoulli numbers B[3,2](n) begin: 1, 1/2, -1/2, -1, 13/10, 5, -121/14, -49, 1093/10, 809, -49205/22, -20317, 61203943/910, 722813, -5580127/2, -34607305, ...
From _Peter Luschny_, Mar 26 2021: (Start)
The generalized Bernoulli numbers as given in the Luschny link are different.
1, -7/2, 23/2, -35, 973/10, -245, 7943/14, -1295, 31813/10, -7721, 288715/22, -13475, 128296423/910, -882557, -4891999/2, 33870025, ...
The numerators of these numbers are in A157811. (End)
		

Crossrefs

Programs

  • Mathematica
    Table[Denominator[3^n*BernoulliB[n, 1/3]], {n, 0, 100}] (* Indranil Ghosh, Jul 18 2017 *)
  • PARI
    a(n) = denominator(3^n * bernfrac(n)); \\ Ruud H.G. van Tol, Jan 31 2024
  • Python
    from sympy import bernoulli, Rational
    def a(n):
        return (3**n * bernoulli(n, Rational(1,3))).as_numer_denom()[1]
    print([a(n) for n in range(101)])  # Indranil Ghosh, Jul 18 2017
    
  • SageMath
    # uses [gen_bernoulli_number from A157811]
    print([denominator((-1)^n*gen_bernoulli_number(n, 3)) for n in range(23)])
    # Peter Luschny, Mar 26 2021
    

Formula

a(n) = denominator(r(n)) with the rationals (in lowest terms) r(n) = Sum_{k=0..n} ((-1)^k / (k+1))*A282629(n, k)*k! = Sum_{k=0..n} ((-1)^k/(k+1))*A284861(n, k). r(n) = B[3,1](n) = 3^n*B(n, 1/3) with the Bernoulli polynomials A196838/A196839 or A053382/A053383.
a(n) = A157800(n)/3^n, n >= 0.

A157799 Numerator of Bernoulli(n, 1/3).

Original entry on oeis.org

1, -1, -1, 1, 13, -5, -121, 49, 1093, -809, -49205, 20317, 61203943, -722813, -5580127, 34607305, 25949996501, -2145998417, -2832495743227, 167317266613, 101471818419863, -16020403322021, -4469253897850313, 1848020950359841, 11126033443528968583, -252778977216700025
Offset: 0

Views

Author

N. J. A. Sloane, Nov 08 2009

Keywords

Comments

This sequence gives also the numerators of the generalized Bernoulli numbers B[3,1](n) = 3^n*Bernoulli(n, 1/3) with denominators given by A285068. See the formula and example section there for the rationals. The numbers B[3,2](n) = 3^n*Bernoulli(n, 2/3) = (-1)^n*B[3,1](n) have numerators (-1)^n*a(n) and denominators A285068 (proof from the e.g.f.s). - Wolfdieter Lang, Apr 28 2017

Crossrefs

For denominators see A157800, A285068.

Programs

  • Mathematica
    Table[Numerator[BernoulliB[n, 1/3]], {n, 0, 50}] (* Vincenzo Librandi, Mar 16 2014 *)
  • PARI
    a(n) = my(x=1/3); numerator(eval(bernpol(n))); \\ Ruud H.G. van Tol, May 10 2024
  • Python
    from sympy import bernoulli, Integer
    def a(n): return bernoulli(n, 1/Integer(3)).numerator # Indranil Ghosh, May 01 2017
    

A157811 Numerator of Bernoulli(n, -2/3).

Original entry on oeis.org

1, -7, 23, -35, 973, -245, 7943, -1295, 31813, -7721, 288715, -13475, 128296423, -882557, -4891999, 33870025, 26217383381, -2149340753, -2830613025019, 167302324405, 101475278720663, -16020469382309, -4469247530896841, 1848020660952865, 11126033993150564743
Offset: 0

Views

Author

N. J. A. Sloane, Nov 08 2009

Keywords

Examples

			From _Peter Luschny_, Mar 26 2021: (Start)
The rational numbers given in the definition start:
1, -7/6, 23/18, -35/27, 973/810, -245/243, 7943/10206, -1295/2187, 31813/65610, -7721/19683, 288715/1299078, -13475/177147, 128296423/483611310, ...
The generalized Bernoulli numbers defined in the Luschny link are different:
1, -7/2, 23/2, -35, 973/10, -245, 7943/14, -1295, 31813/10, -7721, 288715/22, -13475, 128296423/910, -882557, -4891999/2, ... The denominators of these numbers are in A285068. (End)
		

Crossrefs

For denominators see A157800.
The denominators of the generalized Bernoulli numbers are A285068.

Programs

  • Mathematica
    Table[Numerator[BernoulliB[n, -2/3]], {n, 0, 50}] (* Vincenzo Librandi, Mar 16 2014 *)
  • SageMath
    # Generalized Bernoulli polynomials
    def gen_bernoulli_polynomial(n, m, x):
        p = sum(sum(sum(((-1)^(n-v)/(j+1))*binomial(n,k)*binomial(j,v)*(m*(v-x))^k
            for v in (0..j)) for j in (0..k)) for k in (0..n))
        return expand(p)
    # Generalized Bernoulli numbers
    def gen_bernoulli_number(n, m): return gen_bernoulli_polynomial(n, m, 1)
    print([numerator((-1)^n*gen_bernoulli_number(n, 3)) for n in range(23)]) # Peter Luschny, Mar 26 2021

A157801 Numerator of Bernoulli(n, -1/3).

Original entry on oeis.org

1, -5, 11, -10, 133, -10, 131, -70, 1333, 782, -48545, -20350, 61236703, 722774, -5580043, -34607350, 25950004661, 2145998366, -2832495728863, -167317266670, 101471818426463, 16020403321958, -4469253897847277, -1848020950359910, 11126033443529034103, 252778977216699950
Offset: 0

Views

Author

N. J. A. Sloane, Nov 08 2009

Keywords

Crossrefs

For denominators see A157800.

Programs

  • Mathematica
    Numerator[BernoulliB[Range[0,30],-(1/3)]] (* Harvey P. Dale, Nov 17 2012 *)
Showing 1-4 of 4 results.