A013204 E.g.f. log(sech(x) + tan(x)).

0, 1, -2, 7, -24, 165, -1232, 10827, -111104, 1316585, -17449472, 257028847, -4164086784, 73616009805, -1409671718912, 29070305745267, -642304219480064, 15137914082015825, -379068532960919552, 10050622525103392087, -281286704647327186944

Offset

0,3

Links

Matthew House, Table of n, a(n) for n = 0..422

Example

Log(sech(x) + tan(x)) = x -2/2!*x^2 +7/3!*x^3 -24/4!*x^4 +165/5!*x^5 - ...

Mathematica

a[n_] := SeriesCoefficient[Log[Sech[x] + Tan[x]], {x, 0, n}] n!;
With[{nn=20}, CoefficientList[Series[Log[Sech[x]+Tan[x]], {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Oct 19 2018 *)

Crossrefs

Sequence in context: A375129 A330506 A236422 * A013209 A244090 A247880

Adjacent sequences: A013201 A013202 A013203 * A013205 A013206 A013207

Keyword

sign

Author

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

Extensions

a(0)=0 inserted by Alois P. Heinz, Jul 29 2015

Status

approved