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 A351780 #7 Feb 19 2022 13:55:47
%S A351780 1,0,-2,6,108,-2420,8730,1313718,-57930152,567983736,109544982390,
%T A351780 -9917916180590,321821829728388,32383946348733252,
%U A351780 -6591798188344856942,531702135210365508270,11136706526396459006640
%N A351780 a(n) = n! * Sum_{k=0..n} (-k)^(n-k) * (n-k)^k/k!.
%o A351780 (PARI) a(n) = n!*sum(k=0, n, (-k)^(n-k)*(n-k)^k/k!);
%Y A351780 Cf. A351768, A351779.
%K A351780 sign
%O A351780 0,3
%A A351780 _Seiichi Manyama_, Feb 19 2022