A012466 E.g.f. sec(arctan(x)^2) (even powers only).

1, 0, 12, -480, 37968, -4773120, 878319552, -222512349696, 74262725323008, -31578556041732096, 16666719859336276992, -10690478515516973015040, 8190555666463900906475520, -7387658525325188387856384000

Offset: 0

Author

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

Keywords

• sign

Examples

			sec(arctan(x)^2) = =1+12/4!*x^4-480/6!*x^6+37968/8!*x^8+-...
		

Programs

Mathematica

With[{nn=30},Take[CoefficientList[Series[Sec[ArcTan[x]^2],{x,0,nn}],x]Range[0,nn]!,{1,-1,2}]] (* Harvey P. Dale, Jan 12 2013 *)