A012184 sech(tan(arctanh(x)))=1-1/2!*x^2-11/4!*x^4-301/6!*x^6-14839/8!*x^8...

1, -1, -11, -301, -14839, -1109881, -110852675, -12696026981, -1044878845295, 344502726652559, 397767671438223365, 311149018395487011299, 242840543036206414510489, 203578596149994366707196439, 187397387863859771967571124941, 190632732651754400283645304176299

Offset

0,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..40

Mathematica

With[{nn=40}, Take[CoefficientList[Series[Sech[Tan[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jul 22 2014 *)

Crossrefs

Sequence in context: A067424 A001538 A101269 * A012027 A279181 A002114

Adjacent sequences: A012181 A012182 A012183 * A012185 A012186 A012187

Keyword

sign

Author

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

Extensions

More terms from Harvey P. Dale, Jul 22 2014

Status

approved