A064074 Generalized tangent number d(9,n).

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

Offset

1,1

Links

Lars Blomberg, Table of n, a(n) for n = 1..174

D. Shanks, Generalized Euler and class numbers. Math. Comp. 21 (1967) 689-694.

D. Shanks, Corrigenda to: "Generalized Euler and class numbers", Math. Comp. 22 (1968), 699.

Eric Weisstein's World of Mathematics, Tangent Number.

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

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

Crossrefs

Cf. A064070, A349268, A349264.

Sequence in context: A012675 A175014 A101812 * A005249 A177069 A204681

Adjacent sequences: A064071 A064072 A064073 * A064075 A064076 A064077

Keyword

nonn,easy

Author

Eric W. Weisstein, Aug 31 2001

Extensions

Offset changed to 1 by Lars Blomberg, Sep 07 2015

Status

approved