A013535 Numerator of the coefficient [x^(2n)] in the Taylor series sec(cosec(x) - cosech(x)).

1, 1, 5, 5449, 6973, 518819753, 1489058191, 293416964947, 2531578641757, 8778884852410565513, 2503198198587351877067, 2378459715706347981795671, 2343990771779851025499037, 521048260968673067986908628597, 35145358095152621756454620279473

Offset

0,3

Links

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

Example

1 - x^2/18 + x^4/1944 - 5029*x^6/3674160 + 6697*x^8/264539520 - ...

Mathematica

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

Crossrefs

Cf. A068917.

Sequence in context: A177503 A072021 A196627 * A079812 A137694 A292334

Adjacent sequences: A013532 A013533 A013534 * A013536 A013537 A013538

Keyword

nonn,frac

Author

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

Extensions

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

Status

approved