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.

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A285865 Denominator of the coefficient triangle B2(n, m) of generalized Bernoulli polynomials PB2(n, x) read by rows.

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 15, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 21, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 15, 1, 3, 1, 3, 1, 3, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 1, 33, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 0

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Author

Wolfdieter Lang, May 03 2017

Keywords

Comments

The numerator triangle is given in A285864, where details are given.

Examples

			The triangle a(n, m) begins:
n\m   0 1 2 3 4 5 6 7 8 9 10 ...
0:    1
1:    1 1
2:    3 1 1
3:    1 1 1 1
4:   15 1 1 1 1
5:    1 3 1 3 1 1
6:   21 1 1 1 1 1 1
7:    1 3 1 3 1 1 1 1
8:   15 1 3 1 3 1 3 1 1
9:    1 5 1 1 1 5 1 1 1 1
10:  33 1 1 1 1 1 1 1 1 1  1
...
For the triangle of the rationals B2(n, m) see A285864.
		

Crossrefs

Programs

  • Mathematica
    T[n_, m_]:=Denominator[Binomial[n, m]*2^(n - m)*BernoulliB[n - m]]; Table[T[n, m], {n, 0, 20}, {m, 0, n}] // Flatten (* Indranil Ghosh, May 06 2017 *)
  • PARI
    T(n, m) = denominator(binomial(n, m)*2^(n - m)*bernfrac(n - m));
    for(n=0, 20, for(m=0, n, print1(T(n, m),", ");); print();) \\ Indranil Ghosh, May 06 2017
    
  • Python
    from sympy import binomial, bernoulli
    def T(n, m):
        return (binomial(n, m) * 2**(n - m) * bernoulli(n - m)).denominator
    for n in range(21): print([T(n, m) for m in range(n + 1)]) # Indranil Ghosh, May 06 2017

Formula

a(n, m) = denominator(B2(n, m)) with B2(n, m) = binomial(m, m)*2^(n-m)*B(n-m), with the Bernoulli numbers B(k) = A027641(k)/A027642(k).
E.g.f. of the rational column sequences {B2(n, m)}_{n>=0} is 2*x/(exp(2*x) - 1)*x^m/m!. Here a(n, m) are the denominators of the exponentially generated sequence.

A285866 a(n) = numerator((-2)^n*Sum_{k=0..n} binomial(n,k) * Bernoulli(k, 1/2)).

Original entry on oeis.org

1, -2, 11, -6, 127, -10, 221, -14, 367, -18, -1895, -22, 1447237, -26, -57253, -30, 118526399, -34, -5749677193, -38, 91546283957, -42, -1792042789427, -46, 1982765468376757, -50, -286994504449237, -54, 3187598676787485443, -58, -4625594554880206360895, -62
Offset: 0

Views

Author

Wolfdieter Lang, May 03 2017

Keywords

Comments

Previous name: Numerators of alternating row sums of the rational triangle B2 = A285864/A285865.
The denominators are given in A141459.

Crossrefs

Programs

  • Maple
    a := n -> numer((-2)^n*add(binomial(n,k)*bernoulli(k,1/2), k=0..n)):
    seq(a(n), n=0..31); # Peter Luschny, Jul 24 2020
  • Mathematica
    a[n_] := (-2)^n Sum[Binomial[n, k] BernoulliB[k, 1/2], {k, 0, n}] // Numerator;
    Table[a[n], {n, 0, 31}] (* Peter Luschny, Jul 24 2020 *)
  • SageMath
    # uses [gen_bernoulli_number from A157811]
    print([numerator((-1)^n*gen_bernoulli_number(n, 2)) for n in range(33)]) # Peter Luschny, Mar 26 2021

Formula

a(n) = numerator(Sum_{m=0..n} (-1)^m*A285864(n, m)/A285865(n, m)), n >= 0, where the rational triangle is B2(n, m) = binomial(m, m)*2^(n-m)*B(n-m), with the Bernoulli numbers B(k) = A027641(k)/A027642(k).

Extensions

More terms from Indranil Ghosh, May 06 2017
New name by Peter Luschny, Jul 24 2020
Showing 1-2 of 2 results.