A012796 arctan(sec(x)*tan(x))=x+3/3!*x^3-15/5!*x^5-1197/7!*x^7-255/9!*x^9...

1, 3, -15, -1197, -255, 5448003, 241437105, -104019879597, -17849464279935, 5108933510880003, 2525823613297136625, -425245839735677809197, -661733086487793705145215, -4593026819719423131883197

Offset

0,2

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[ArcTan[Sec[x] Tan[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, May 22 2017 *)

Crossrefs

Sequence in context: A029521 A272353 A012766 * A231656 A096368 A016066

Adjacent sequences: A012793 A012794 A012795 * A012797 A012798 A012799

Keyword

sign

Author

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

Status

approved