A009840 Expansion of tanh(x)/cos(sin(x)).

1, 1, 1, -167, 289, -30799, 7624865, -327166135, 29995758529, -7060555404191, 991934013190081, -177889548504511175, 51940497621294961121, -14246314907147632709615, 4386830634217402797858657

Offset

0,4

Links

Table of n, a(n) for n=0..14.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tanh[x]/Cos[Sin[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Jan 13 2024 *)

Crossrefs

Sequence in context: A065216 A142485 A046008 * A033255 A052233 A142431

Adjacent sequences: A009837 A009838 A009839 * A009841 A009842 A009843

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Previous Mathematica program replaced by Harvey P. Dale, Jan 13 2024

Status

approved