A012044 sec(sin(arcsinh(x)))=1+1/2!*x^2-3/4!*x^4+21/6!*x^6-647/8!*x^8...

1, 1, -3, 21, -647, 45161, -4655115, 671831421, -131445679375, 33601481453521, -10874248371483155, 4345212201159011301, -2101132542287329737623, 1209250716473417141359161

Offset

0,3

Links

Table of n, a(n) for n=0..13.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sec[Sin[ArcSinh[x]]], {x, 0, nn}], x]Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Nov 28 2011 *)

Crossrefs

Sequence in context: A180999 A181003 A093549 * A350513 A098918 A001699

Adjacent sequences: A012041 A012042 A012043 * A012045 A012046 A012047

Keyword

sign

Author

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

Status

approved