A302579 Expansion of e.g.f. exp(cosh(x)/cos(x)-1) (even powers only).

1, 2, 24, 632, 28784, 1991552, 193410624, 24993180032, 4134783110144, 850499728758272, 212579274719007744, 63381008507902595072, 22200896917210834817024, 9019985888570141052280832, 4204783981520054371872374784, 2228007853953954434037178007552

Offset

0,2

Links

Table of n, a(n) for n=0..15.

N. J. A. Sloane, Transforms

Formula

a(n) = (2*n)! * [x^(2*n)] exp(cosh(x)/cos(x)-1).

Example

exp(cosh(x)/cos(x)-1) = 1 + 2*x^2/2! + 24*x^4/4! + 632*x^6/6! + 28784*x^8/8! + ...

Mathematica

nmax = 15; Table[(CoefficientList[Series[Exp[Cosh[x]/Cos[x] - 1], {x, 0, 2 nmax}], x] Range[0, 2 nmax]!)[[n]], {n, 1, 2 nmax + 1, 2}]

Crossrefs

Cf. A000795, A005046, A006229, A009234, A009253, A009254, A009274, A012853, A217502.

Sequence in context: A009447 A193442 A123741 * A012216 A012118 A012375

Adjacent sequences: A302576 A302577 A302578 * A302580 A302581 A302582

Keyword

nonn

Author

Ilya Gutkovskiy, Apr 10 2018

Status

approved