A012873 Expansion of e.g.f.: arctan(sech(x)*log(x+1))=x-1/2!*x^2-3/3!*x^3+12/4!*x^4+43/5!*x^5...

0, 1, -1, -3, 12, 43, -555, -49, 37632, -154867, -3817845, 45540649, 409535148, -12690409929, -14813266559, 3983011043675, -28691304331680, -1331245986549447, 25689766775914647, 419731311262402229, -19155172571527380500, -49768220393610527069, 13990749024453019691565

Offset

1,4

Links

Table of n, a(n) for n=1..23.

Mathematica

With[{nn=20}, CoefficientList[Series[ArcTan[Sech[x]Log[x+1]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Aug 14 2021 *)

Crossrefs

Sequence in context: A366617 A375203 A290918 * A282082 A356888 A167477

Adjacent sequences: A012870 A012871 A012872 * A012874 A012875 A012876

Keyword

sign

Author

Patrick Demichel

Extensions

Zero prepended to sequence and definition clarified by Harvey P. Dale, Aug 14 2021

a(21)-a(23) from Stefano Spezia, Feb 03 2026

Status

approved