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 A367886 #11 Dec 04 2023 06:35:25
%S A367886 1,0,6,27,324,3645,54918,923643,18061704,394663833,9607469130,
%T A367886 256997250279,7502660832780,237243300445125,8079508278302958,
%U A367886 294800526215739315,11473728720705019152,474469344621574172721,20774758472643152149650
%N A367886 Expansion of e.g.f. 1/(1 - x * (exp(3*x) - 1)).
%F A367886 a(0) = 1; a(n) = n * Sum_{k=2..n} 3^(k-1) * binomial(n-1,k-1) * a(n-k).
%F A367886 a(n) = n! * Sum_{k=0..floor(n/2)} 3^(n-k) * k! * Stirling2(n-k,k)/(n-k)!.
%o A367886 (PARI) a(n) = n!*sum(k=0, n\2, 3^(n-k)*k!*stirling(n-k, k, 2)/(n-k)!);
%Y A367886 Cf. A052848, A367885.
%Y A367886 Cf. A337039, A351737.
%K A367886 nonn
%O A367886 0,3
%A A367886 _Seiichi Manyama_, Dec 04 2023