A012879 - OEIS

A012879

Expansion of e.g.f.: exp(sech(x)*arctan(x))=1+x+1/2!*x^2-4/3!*x^3-19/4!*x^4+20/5!*x^5...

1, 1, 1, -4, -19, 20, 565, 1024, -24743, -147568, 1450985, 19148736, -100090043, -2934842560, 5608180253, 551525234688, 703874231473, -127249126657792, -601015521145391, 35789287036394496, 309193460848468125

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,4

LINKS

Table of n, a(n) for n=0..20.

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Exp[Sech[x]ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Dec 22 2017 *)

CROSSREFS

Sequence in context: A070612 A165820 A043056 * A072178 A116980 A296602

Adjacent sequences: A012876 A012877 A012878 * A012880 A012881 A012882

KEYWORD

sign

AUTHOR

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

EXTENSIONS

Definition clarified by Harvey P. Dale, Dec 22 2017

STATUS

approved