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 A368272 #8 Dec 19 2023 09:16:28
%S A368272 1,-2,3,-1,-11,19,151,-799,-2295,37367,-16469,-2114531,9695533,
%T A368272 132142451,-1556927553,-6822608311,234527654161,-360436983569,
%U A368272 -35798255259821,294290464165685,5217729367883061,-102317187098688661,-517822188623299097,31412148276241662049
%N A368272 Expansion of e.g.f. exp(-x) / (1 + x*exp(x)).
%F A368272 a(n) = n! * Sum_{k=0..n} (-1)^(n-k) * (n-k-1)^k / k!.
%o A368272 (PARI) a(n) = n!*sum(k=0, n, (-1)^(n-k)*(n-k-1)^k/k!);
%Y A368272 Cf. A302397, A368271, A368273.
%K A368272 sign,easy
%O A368272 0,2
%A A368272 _Seiichi Manyama_, Dec 19 2023