A009812 Expansion of tanh(tan(x))*tan(x).

0, 2, 8, 48, 384, 18944, 2364416, 271337472, 29986947072, 3404290850816, 424605895884800, 64805172535099392, 13431502292801028096, 3690128527895627300864, 1195824827744772864081920, 422661100917064376002805760, 160940944285147928359021314048

Offset

0,2

Links

Table of n, a(n) for n=0..16.

Mathematica

With[{nn=40}, Take[CoefficientList[Series[Tanh[Tan[x]]*Tan[x] , {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Feb 26 2015 *)

Crossrefs

Sequence in context: A370677 A370936 A109664 * A232005 A351422 A229233

Adjacent sequences: A009809 A009810 A009811 * A009813 A009814 A009815

Keyword

nonn

Author

R. H. Hardin

Extensions

Extended and signs tested Mar 15 1997 by Olivier Gérard.

More terms from and prior Mathematica program replaced by Harvey P. Dale, Feb 26 2015

Status

approved