A013540 Numerator of the coefficient [x^(2n+1)] of the Taylor series arctan(cosec(x) - coth(x)).

-1, 7, -17, 913, -93959, 9405719, -8909477, 211410621413, -6740064210937, 2805742760628347, -761503407533329723, 340317674208644677253, -38791272133810800467, 1468818906393936912860264741

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..200

Example

-x/6 + 7*x^3/162 - 17*x^5/13608 + 913*x^7/1224720 - 93959*x^9/1745960832 + ...

Mathematica

Numerator[Take[CoefficientList[Series[ArcTan[Csc[x] - Coth[x]], {x, 0, 26}], x], {2, -1, 2}]] (* G. C. Greubel, Nov 13 2016 *)

Crossrefs

Sequence in context: A102266 A113765 A269447 * A153375 A001145 A093139

Adjacent sequences: A013537 A013538 A013539 * A013541 A013542 A013543

Keyword

sign,frac

Author

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

Extensions

Name edited by R. J. Mathar, Dec 21 2011

Status

approved