A012461 sinh(arctan(x)*arctan(x))=2/2!*x^2-16/4!*x^4+488/6!*x^6-30336/8!*x^8...

0, 2, -16, 488, -30336, 3061152, -450481920, 90676698240, -23889578496000, 7972943138664960, -3286129765438771200, 1638857583672607549440, -972524875970827007262720, 677113960144029088030433280

Offset: 0

Author

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

Keywords

• sign

Programs

Mathematica

nn = 20; Table[(CoefficientList[Series[Sinh[ArcTan[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Feb 08 2015 *)

Extensions

a(0)=0 prepended by Vaclav Kotesovec, Feb 08 2015