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 A367308 #6 Nov 13 2023 04:11:13
%S A367308 1,1,6,66,1220,34130,1346982,71335236,4883183496,419708936862,
%T A367308 44256845856410,5618131203742376,845200046197677612,
%U A367308 148704124317985161666,30252055409619038022510,7046807010054413604547740,1863423940527969873383134736,555177557057715635856129878246
%N A367308 a(0) = 1; thereafter a(n) = n*Sum_{k=0..n-1} binomial(n,k) * a(k).
%F A367308 a(n) ~ c * n^(2*n + 3/2) / exp(2*n), where c = 6.702694897473369225159542571434998226159280485652114977020519335049605...
%t A367308 a[n_] := a[n] = If[n==0, 1, n*Sum[Binomial[n, k]*a[k], {k, 0, n-1}]]; Table[a[n], {n, 0, 20}]
%Y A367308 Cf. A365863.
%K A367308 nonn
%O A367308 0,3
%A A367308 _Vaclav Kotesovec_, Nov 13 2023