A013257 Expansion of e.g.f.: sech(log(x+1)-arctan(x))=1-3/4!*x^4+40/5!*x^5-250/6!*x^6+840/7!*x^7...

1, 0, 0, 0, -3, 40, -250, 840, -4095, 66960, -470700, -2908400, 57705725, 17230200, 273271050, -194550993000, 2844134918625, 11555861044000, -303831545875000, -10640259365580000, 157518220758868125

Offset

0,5

Links

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

Mathematica

With[{nn=20}, CoefficientList[Series[Sech[Log[x+1]-ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Oct 24 2020 *)

Crossrefs

Sequence in context: A197247 A065815 A283115 * A013250 A013255 A013256

Adjacent sequences: A013254 A013255 A013256 * A013258 A013259 A013260

Keyword

sign

Author

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

Extensions

Definition clarified by Harvey P. Dale, Oct 24 2020

Status

approved