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.

A330046 Expansion of e.g.f. exp(x) / (1 - sinh(x)).

Original entry on oeis.org

1, 2, 5, 17, 77, 437, 2975, 23627, 214457, 2189897, 24846395, 310095887, 4221990437, 62273111357, 989164604615, 16834483468547, 305604501324017, 5894522593612817, 120381876933435635, 2595103478745235607, 58887707028270711197, 1403084759749993342277
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 28 2019

Keywords

Comments

Binomial transform of A006154.

Crossrefs

Programs

  • Mathematica
    nmax = 21; CoefficientList[Series[Exp[x]/(1 - Sinh[x]), {x, 0, nmax}], x] Range[0, nmax]!

Formula

a(n) = Sum_{k=0..n} binomial(n,k) * A006154(k).
a(n) ~ n! * (1 + 1/sqrt(2)) / (log(1 + sqrt(2)))^(n+1). - Vaclav Kotesovec, Dec 03 2019

A348587 Expansion of e.g.f. exp(x) / (2 - cos(x)).

Original entry on oeis.org

1, 1, 0, -2, 2, 26, -30, -622, 982, 25846, -50910, -1639142, 3874862, 147434366, -406614390, -17851478062, 56266545142, 2799621404086, -9927225631470, -552054087163382, 2175042302117822, 133686372253841006, -579383205000618150, -39002628245713951102
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 24 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 23; CoefficientList[Series[Exp[x]/(2 - Cos[x]), {x, 0, nmax}], x] Range[0, nmax]!
  • PARI
    my(x='x+O('x^40)); Vec(serlaplace(exp(x)/(2-cos(x)))) \\ Michel Marcus, Oct 24 2021

Formula

a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(n,2*k) * A094088(k).

A214407 Triangle read by rows. The coefficients in ascending order of x^i of the polynomials p{0}(x) = 1 and p{n}(x) = Sum_{k=0..n-1; k even} binomial(n, k) * p{k}(0)*(1 - n%2 + x^(n - k)).

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 0, 3, 0, 1, 7, 0, 6, 0, 1, 0, 35, 0, 10, 0, 1, 121, 0, 105, 0, 15, 0, 1, 0, 847, 0, 245, 0, 21, 0, 1, 3907, 0, 3388, 0, 490, 0, 28, 0, 1, 0, 35163, 0, 10164, 0, 882, 0, 36, 0, 1, 202741, 0, 175815, 0, 25410, 0, 1470, 0, 45, 0, 1, 0
Offset: 0

Views

Author

Peter Luschny, Jul 16 2012

Keywords

Comments

Matrix inverse of a signed variant of A119467.

Examples

			1
0, 1
1, 0, 1
0, 3, 0, 1
7, 0, 6, 0, 1
0, 35, 0, 10, 0, 1
121, 0, 105, 0, 15, 0, 1
0, 847, 0, 245, 0, 21, 0, 1
3907, 0, 3388, 0, 490, 0, 28, 0, 1
		

Crossrefs

Cf. A119467, A327034 (row sums), A094088 (column 0).

Programs

  • Sage
    @CachedFunction
    def A214407_poly(n, x) :
        return 1 if n==0 else add(A214407_poly(k, 0)*binomial(n, k)*(x^(n-k)+1-n%2) for k in range(n)[::2])
    def A214407_row(n) :
        R = PolynomialRing(ZZ, 'x')
        return R(A214407_poly(n,x)).coeffs()
    for n in (0..8) : A214407_row(n)

Formula

T(n, k) = n! * [y^k] [x^n] (exp(x * y) / (2 - cosh(x))). - Peter Luschny, May 06 2023
Showing 1-3 of 3 results.