This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A009439 #18 Sep 08 2023 04:04:16
%S A009439 0,1,-3,8,-16,29,-191,1980,-14456,85713,-657171,7877880,-97759608,
%T A009439 1100545341,-13021637695,185198054748,-2933940050000,46990261427073,
%U A009439 -774002505048195,13811029423532424,-266175983849182016
%N A009439 Expansion of e.g.f. log(1+x)/exp(tanh(x)).
%H A009439 G. C. Greubel, <a href="/A009439/b009439.txt">Table of n, a(n) for n = 0..448</a>
%t A009439 With[{nn=20},CoefficientList[Series[Log[1+x]/Exp[Tanh[x]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, May 19 2023 *)
%o A009439 (Magma)
%o A009439 R<x>:=PowerSeriesRing(Rationals(), 30);
%o A009439 [0] cat Coefficients(R!(Laplace( Log(1+x)*Exp(-Tanh(x)) ))); // _G. C. Greubel_, Sep 08 2023
%o A009439 (SageMath)
%o A009439 def A009439_list(prec):
%o A009439 P.<x> = PowerSeriesRing(QQ, prec)
%o A009439 return P( log(1+x)*exp(-tanh(x)) ).egf_to_ogf().list()
%o A009439 A009439_list(31) # _G. C. Greubel_, Sep 08 2023
%Y A009439 Cf. A009405 - A009420, A009422 - A009438.
%K A009439 sign,easy
%O A009439 0,3
%A A009439 _R. H. Hardin_
%E A009439 Extended with signs by _Olivier Gérard_, Mar 15 1997
%E A009439 Definition clarified and previous Mathematica program replaced by _Harvey P. Dale_, May 19 2023