A009386 Expansion of log(1+tanh(tan(x))).

0, 1, -1, 2, -6, 16, -72, 272, -1456, 7936, -47104, 353792, -2390784, 22368256, -180612096, 1903757312, -18625189888, 209865342976, -2431403622400, 29088885112832, -384624656646144, 4951498053124096, -72343735465672704

Offset

0,4

Links

Table of n, a(n) for n=0..22.

Mathematica

Log[ 1+Tanh[ Tan[ x ] ] ]
CoefficientList[Series[Log[1 + Tanh[Tan[x]]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

Crossrefs

Cf. A000182.

Sequence in context: A150032 A283420 A121749 * A009605 A009681 A009186

Adjacent sequences: A009383 A009384 A009385 * A009387 A009388 A009389

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved