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 A368295 #8 Dec 20 2023 12:36:53
%S A368295 1,0,7,47,549,7859,134743,2694537,61595593,1584039383,45262146411,
%T A368295 1422647401493,48780718512397,1812012517295811,72486789793754911,
%U A368295 3106846273709042609,142039582571511632529,6899664100487740573871,354870658975988082859219
%N A368295 Expansion of e.g.f. exp(-x) / (1 - x*exp(3*x)).
%F A368295 a(n) = n! * Sum_{k=0..n} (3*(n-k)-1)^k / k!.
%o A368295 (PARI) a(n) = n!*sum(k=0, n, (3*(n-k)-1)^k/k!);
%Y A368295 Cf. A092148, A368294.
%K A368295 nonn,easy
%O A368295 0,3
%A A368295 _Seiichi Manyama_, Dec 20 2023