A012454 sec(arctan(x)*tan(x))=1+12/4!*x^4+17360/8!*x^8-241920/10!*x^10...

1, 0, 12, 0, 17360, -241920, 186158016, -11413642240, 7726026430720, -1212323504480256, 892608906281741312, -274005660019568705536, 234514059257417538031616, -119571044071522301122641920

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sec[ArcTan[x]Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jan 12 2016 *)

Crossrefs

Sequence in context: A012338 A012453 A284453 * A322732 A370332 A370432

Adjacent sequences: A012451 A012452 A012453 * A012455 A012456 A012457

Keyword

sign

Author

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

Status

approved