A012243 -log(cos(arctanh(x)))=1/2!*x^2+10/4!*x^4+280/6!*x^6+15440/8!*x^8...

1, 10, 280, 15440, 1412480, 193606400, 37162777600, 9519986944000, 3139364220928000, 1295834618224640000, 654668849830461440000, 397456058751397068800000, 285567610965661253632000000

Offset

0,2

Links

Table of n, a(n) for n=0..12.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[-Log[Cos[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn]!, {3, -1, 2}]] (* Harvey P. Dale, May 28 2017 *)

Crossrefs

Sequence in context: A251580 A165457 A025035 * A186270 A231793 A213403

Adjacent sequences: A012240 A012241 A012242 * A012244 A012245 A012246

Keyword

nonn

Author

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

Extensions

Edited by D. S. McNeil, Dec 17 2011

Status

approved