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 A367983 #10 Jun 11 2024 19:09:36
%S A367983 1,1,33,481,11457,329281,11405793,460726561,21270068097,1104703800961,
%T A367983 63750028379553,4046761389279841,280235644230863937,
%U A367983 21023317859012763841,1698493239420829750113,147024466409751282556321,13575133989036437786590977,1331764937006253524751217921
%N A367983 Expansion of e.g.f. exp(-3*x) / (2 - exp(4*x)).
%H A367983 G. C. Greubel, <a href="/A367983/b367983.txt">Table of n, a(n) for n = 0..345</a>
%F A367983 a(n) = Sum_{k>=0} (4*k-3)^n / 2^(k+1).
%F A367983 a(n) = (-3)^n + Sum_{k=1..n} binomial(n,k) * 4^k * a(n-k).
%F A367983 a(n) = Sum_{k=0..n} binomial(n,k) * (-3)^(n-k) * 4^k * A000670(k).
%t A367983 nmax = 17; CoefficientList[Series[Exp[-3 x]/(2 - Exp[4 x]), {x, 0, nmax}], x] Range[0, nmax]!
%t A367983 a[n_] := a[n] = (-3)^n + Sum[Binomial[n, k] 4^k a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 17}]
%o A367983 (Magma)
%o A367983 R<x>:=PowerSeriesRing(Rationals(), 30);
%o A367983 Coefficients(R!(Laplace( Exp(-3*x)/(2-Exp(4*x)) ))); // _G. C. Greubel_, Jun 11 2024
%o A367983 (SageMath)
%o A367983 def A367983_list(prec):
%o A367983 P.<x> = PowerSeriesRing(QQ, prec)
%o A367983 return P( exp(-3*x)/(2-exp(4*x)) ).egf_to_ogf().list()
%o A367983 A367983_list(40) # _G. C. Greubel_, Jun 11 2024
%Y A367983 Cf. A000670, A328183, A346208, A355220, A367977, A367979, A367980, A367981, A367982.
%K A367983 nonn
%O A367983 0,3
%A A367983 _Ilya Gutkovskiy_, Dec 07 2023