A012456 exp((arctan(x))^2)=1+2/2!*x^2-4/4!*x^4+8/6!*x^6+912/8!*x^8...

1, 2, -4, 8, 912, -99168, 11815872, -1790856576, 347783278848, -85244795874816, 25888104843574272, -9570587679263078400, 4239434238319441121280, -2218976274384029204766720

Offset

0,2

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Exp[ArcTan[x]^2], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Apr 24 2016 *)

Crossrefs

Sequence in context: A061089 A067499 A135212 * A071686 A296742 A103097

Adjacent sequences: A012453 A012454 A012455 * A012457 A012458 A012459

Keyword

sign

Author

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

Extensions

Definition clarified by Harvey P. Dale, Apr 24 2016

Status

approved