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 A380229 #11 Jan 17 2025 09:05:21
%S A380229 1,1,5,32,258,2518,28733,374188,5465748,88364877,1564525351,
%T A380229 30076618014,623362069525,13846300701886,327952448024833,
%U A380229 8246654495001815,219323630123687561,6148716950721967215,181171993247893669702,5595764936875993028696,180742802515427561158060,6092097271225726649472555
%N A380229 Expansion of e.g.f. exp( exp( (exp(3*x)-1)/3 ) - 1 ).
%F A380229 a(n) = Sum_{k=0..n} 3^(n-k) * Stirling2(n,k) * Bell(k).
%o A380229 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(exp((exp(3*x)-1)/3)-1)))
%Y A380229 Cf. A000258, A380228.
%Y A380229 Cf. A369783.
%K A380229 nonn
%O A380229 0,3
%A A380229 _Seiichi Manyama_, Jan 17 2025