A013533 Numerator of [x^(2n+1)] in the Taylor expansion arctan(cosec(x) - cosech(x)).

1, -1, 67, -319, 172747, -5036627, 12689179, -142848518639, 9522619510673, -15014600586761717, 98523462918652219853, -281638034717631160979, 20971906033995645898061, -1307646596002305911998781633

Offset

0,3

Links

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

Example

x/3 - x^3/81 + 67*x^5/13608 - 319*x^7/612360 + 172747*x^9/1745960832 - ...

Mathematica

Numerator[Take[CoefficientList[Series[ArcTan[Csc[x] - Csch[x]], {x, 0, 25}], x], {2, -1, 2}]] (* G. C. Greubel, Nov 12 2016 *)

Crossrefs

Cf. A068917.

Sequence in context: A270615 A142804 A033242 * A012865 A026911 A142371

Adjacent sequences: A013530 A013531 A013532 * A013534 A013535 A013536

Keyword

sign,frac

Author

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

Extensions

Name edited by R. J. Mathar, Dec 20 2011

Status

approved