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 A366298 #5 Oct 08 2023 09:25:21
%S A366298 1,6,58,828,15766,375276,10719118,357202068,13603819126,582854637276,
%T A366298 27747071520478,1453003753611108,83005119616449286,
%U A366298 5136947527401250476,342365553703113120238,24447711909762202272948,1862151878019906517540246,150702660087903415402794876,12913688931657425188926182398
%N A366298 Expansion of e.g.f. 1 / (-2 + Sum_{k=1..3} exp(-k*x)).
%F A366298 a(0) = 1; a(n) = Sum_{k=1..n} (-1)^(k+1) * binomial(n,k) * (1 + 2^k + 3^k) * a(n-k).
%t A366298 nmax = 18; CoefficientList[Series[1/(-2 + Sum[Exp[-k x], {k, 1, 3}]), {x, 0, nmax}], x] Range[0, nmax]!
%t A366298 a[0] = 1; a[n_] := a[n] = Sum[(-1)^(k + 1) Binomial[n, k] (1 + 2^k + 3^k) a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 18}]
%Y A366298 Cf. A001550, A004701, A005923, A319509, A366299, A366300, A366301, A366302.
%K A366298 nonn
%O A366298 0,2
%A A366298 _Ilya Gutkovskiy_, Oct 06 2023