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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A349268 Generalized Euler numbers, a(n) = n!*[x^n](sec(9*x)*(4*sin(3*x) + 2)*cos(3*x)^2).

Original entry on oeis.org

2, 12, 126, 2160, 49410, 1415232, 48649086, 1951153920, 89434106370, 4611775398912, 264235243691646, 16653520425185280, 1145011717430672130, 85285640517460180992, 6841110155700330881406, 587950108643300554506240, 53899295662946509072626690, 5249943672359370392053481472
Offset: 0

Views

Author

Peter Luschny, Nov 21 2021

Keywords

Comments

For references and cross references, compare the overview in A349264.

Crossrefs

Row 9 of A349271.
Bisections: A064070, A064074.
Cf. A349264.

Programs

  • Maple
    sec(9*x)*(4*sin(3*x) + 2)*cos(3*x)^2: series(%, x, 20): seq(n!*coeff(%, x, n), n = 0..17);
  • Mathematica
    m = 17; CoefficientList[Series[Sec[9*x] * (4 * Sin[3*x] + 2) * Cos[3*x]^2, {x, 0, m}], x] * Range[0, m]! (* Amiram Eldar, Nov 21 2021 *)

A064074 Generalized tangent number d(9,n).

Original entry on oeis.org

12, 2160, 1415232, 1951153920, 4611775398912, 16653520425185280, 85285640517460180992, 587950108643300554506240, 5249943672359370392053481472, 58942155612887708094647422156800, 812681867463337890406273965833060352, 13499458606943117379769406368204676136960
Offset: 1

Views

Author

Eric W. Weisstein, Aug 31 2001

Keywords

Crossrefs

Programs

  • Maple
    egf := sec(9*x)*4*sin(3*x)*cos(3*x)^2: ser := series(egf, x, 24):
    seq((2*n-1)!*coeff(ser, x, 2*n-1), n = 1..10); # Peter Luschny, Nov 21 2021

Formula

a(n) = (2*n-1)!*[x^(2*n-1)](sec(9*x)*4*sin(3*x)*cos(3*x)^2). - Peter Luschny, Nov 21 2021

Extensions

Offset changed to 1 by Lars Blomberg, Sep 07 2015
Previous Showing 21-22 of 22 results.