A013150 sec(tanh(x)+arctan(x))=1+4/2!*x^2+48/4!*x^4+1344/6!*x^6+71680/8!*x^8...

1, 4, 48, 1344, 71680, 6134144, 766639104, 132845576192, 30189756186624, 8791995173601280, 3164834039610834944, 1391075516277863612416, 727593505575051704926208, 449845963881833812549697536

Offset

0,2

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sec[Tanh[x]+ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jan 17 2024 *)

Crossrefs

Sequence in context: A166231 A191952 A013145 * A353922 A332865 A346949

Adjacent sequences: A013147 A013148 A013149 * A013151 A013152 A013153

Keyword

nonn

Author

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

Status

approved