A009264 Expansion of e.g.f.: exp(tanh(x))/cos(x).

1, 1, 2, 2, 4, 12, 128, 464, 1296, 336, 85600, 838752, 4372160, -11036608, 148860416, 5128035072, 54261590272, -109537337088, -1474575037952, 68456854604288, 1579094994228224, 1239349299477504, -145025202842173440

Offset: 0

Author

R. H. Hardin

Keywords

• sign
• easy

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..480

Programs

Mathematica

With[{nn=30},CoefficientList[Series[Exp[Tanh[x]]/Cos[x],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Mar 14 2018 *)

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Definition clarified and prior Mathematica program replaced by Harvey P. Dale, Mar 14 2018