A012222 Expansion of e.g.f.: exp(arctan(tanh(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, -1243, -40415, 58001, 4825121, -1956083, -866056815, -740509639, 218527875281, 509169335477, -73838559553215, -295854887910879, 32207514779999041, 189240977761969437

Offset

0,4

Links

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

Mathematica

With[{nn=20}, CoefficientList[Series[Exp[ArcTan[Tanh[x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Mar 17 2025 *)

Crossrefs

Sequence in context: A295938 A096742 A012256 * A069267 A348411 A059270

Adjacent sequences: A012219 A012220 A012221 * A012223 A012224 A012225

Keyword

sign

Author

Patrick Demichel

Extensions

Definition clarified by Harvey P. Dale, Mar 17 2025

Status

approved