A102064 Numerators of e.g.f.: -cot(arctanh(x)), odd powers only.

2, 4, 1040, 4640, 331520, 178470400, 24593254400, 666964480000, 66553013755904000, 4091041782710272000, 5311565147410595840000, 211592629697932820480000, 121215491006931795968000000

Offset

1,1

Links

Table of n, a(n) for n=1..13.

Example

cot(arctanh(x)) = 1/x - (2/3)*x - (4/3)*x^3/3! - (1040/63)*x^5/5! - ...

Mathematica

With[{nn=30}, Take[Numerator[CoefficientList[Series[-Cot[ArcTanh[x]], {x, 0, nn}], x] Range[0, nn-1]!], {2, -1, 2}]]//Quiet (* Harvey P. Dale, Jul 08 2017 *)

Crossrefs

Denominators are in A102065.

Sequence in context: A009562 A045647 A219452 * A085638 A134718 A328313

Adjacent sequences: A102061 A102062 A102063 * A102065 A102066 A102067

Keyword

nonn,frac

Author

Ralf Stephan, Dec 28 2004

Status

approved