A009617 Expansion of e.g.f. sinh(tanh(x)*tan(x))/2 in odd powers of x^2.

1, 116, 202576, 1557978176, 34206677698816, 1706222428480541696, 167325183704890858786816, 29168516299952885066683006976, 8389219957754997383106354075467776, 3758865858584530123647466441487099887616, 2506919694437630172543194103107513029881757696

Offset

0,2

Links

Andrew Howroyd, Table of n, a(n) for n = 0..100

Example

x^2/2! + 116*x^6/6! + 202576*x^10/10! + 1557978176*x^14/14! ...

Mathematica

Sinh[ Tanh[ x ]*Tan[ x ] ]/2 (* [ x^(4n+2) ] *)

Prog

(PARI) seq(n)={my(A=O(x^(4*n+2))); Vec(substpol(serlaplace( sinh(tanh(x + A)*tan(x + A))/2 )/x^2, x^4, x))} \\ Andrew Howroyd, Jan 12 2025

Crossrefs

Cf. A012671.

Sequence in context: A296360 A035814 A284377 * A201728 A009687 A373582

Adjacent sequences: A009614 A009615 A009616 * A009618 A009619 A009620

Keyword

nonn,changed

Author

R. H. Hardin

Extensions

Extended and signs tested 03/97.

a(9) onwards from Andrew Howroyd, Jan 12 2025

Status

approved