A012256 Expansion of e.g.f.: exp(tanh(arctan(x)))=1+x+1/2!*x^2-3/3!*x^3-15/4!*x^4+41/5!*x^5...

1, 1, 1, -3, -15, 41, 561, -1019, -38623, 12305, 4206881, 7478221, -661302639, -3005647943, 140958927825, 1143787246421, -38921417469119, -494108406644959, 13433349471318337, 250135591701350045

Offset

0,4

Links

Table of n, a(n) for n=0..19.

Mathematica

With[{nn=20}, CoefficientList[Series[Exp[Tanh[ArcTan[x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Dec 20 2022 *)

Crossrefs

Sequence in context: A249835 A295938 A096742 * A012222 A069267 A348411

Adjacent sequences: A012253 A012254 A012255 * A012257 A012258 A012259

Keyword

sign

Author

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

Extensions

Definition clarified by Harvey P. Dale, Dec 20 2022

Status

approved