A012443 sech(arctan(x)*arcsin(x))=1-12/4!*x^4+120/6!*x^6-1008/8!*x^8...

1, 0, -12, 120, -1008, -45120, -11491392, 1378925184, -443544192768, 53698137606144, -32840379055537152, 7093049054642411520, -6636093887068155801600, 2065820944848385959936000

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcTan[x]ArcSin[x]], {x, 0, nn}], x]Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, May 01 2012 *)

Crossrefs

Sequence in context: A268634 A061506 A059155 * A012274 A009035 A009140

Adjacent sequences: A012440 A012441 A012442 * A012444 A012445 A012446

Keyword

sign

Author

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

Status

approved