A009762 Expansion of tan(x)/cosh(tan(x)).

1, -1, -19, -253, -1415, 164999, 15064037, 949320395, 44870780017, 1646995429391, 436144142262365, 216025221401835155, 72522443306062946281, 18012134571875515731095, 2730160186702754555432789

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tan[x]/Cosh[Tan[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Nov 20 2018 *)

Crossrefs

Sequence in context: A021202 A125454 A293917 * A017952 A055433 A185425

Adjacent sequences: A009759 A009760 A009761 * A009763 A009764 A009765

Keyword

sign

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Prior Mathematica program replaced by Harvey P. Dale, Nov 20 2018

Status

approved