A012178 cos(tan(arctanh(x)))=1-1/2!*x^2-15/4!*x^4-561/6!*x^6-38623/8!*x^8...

1, -1, -15, -561, -38623, -4206881, -661302639, -140958927825, -38921417469119, -13433349471318337, -5625858245527551439, -2783882722627688439921, -1585166024021465157765535

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Cos[Tan[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jun 17 2014 *)

Crossrefs

Sequence in context: A255956 A115918 A110840 * A012229 A212931 A027462

Adjacent sequences: A012175 A012176 A012177 * A012179 A012180 A012181

Keyword

sign

Author

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

Status

approved