A013007 sec(arctan(x)+tan(x))=1+4/2!*x^2+80/4!*x^4+4384/6!*x^6+436992/8!*x^8...

1, 4, 80, 4384, 436992, 70425984, 16592126976, 5395435991040, 2312302178205696, 1263775007737085952, 857643638399523454976, 707659940568946007474176, 697634806106676807565574144

Offset

0,2

Links

Table of n, a(n) for n=0..12.

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, Aug 26 2016 *)

Crossrefs

Sequence in context: A013090 A012042 A013139 * A013008 A013180 A322751

Adjacent sequences: A013004 A013005 A013006 * A013008 A013009 A013010

Keyword

nonn

Author

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

Status

approved