A012548 Expansion of e.g.f. arctan(sinh(x)*tan(x)) (even powers only).

0, 2, 12, -98, -16968, -780838, 93371652, 31402903222, 2306688997872, -1741952370835918, -849143623135762308, -14075683397521166258, 228742196475611564627112, 136676421833398225367464202, -34106209758743782233592937868, -128144470665734286260829913072538

Offset

0,2

Links

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

Example

0/0!*x^0 + 2/2!*x^2 + 12/4!*x^4 - 98/6!*x^6 - 16968/8!*x^8 ...

Maple

egf := arctan(tan(x)*sinh(x)): ser := series(egf, x, 33):
seq((2*n)!*coeff(ser, x, 2*n), n = 0..15); # Peter Luschny, Apr 23 2024

Mathematica

With[{nn=30}, Take[CoefficientList[Series[ArcTan[Sinh[x]Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Oct 17 2015 *)

Crossrefs

Cf. A012816.

Sequence in context: A231173 A303203 A372154 * A012550 A009816 A227084

Adjacent sequences: A012545 A012546 A012547 * A012549 A012550 A012551

Keyword

sign

Author

Patrick Demichel (patrick.demichel(AT)hp.com)

Extensions

Missing a(0) = 0 prepended and new name by Peter Luschny, Apr 23 2024

Status

approved