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 A367473 #10 Nov 19 2023 08:24:58
%S A367473 1,9,117,1953,39645,946089,25926597,801869553,27618402285,
%T A367473 1048096422009,43444114011477,1952712851250753,94592798546953725,
%U A367473 4912513525545837129,272265236648295312357,16039329591716508497553,1000809252891040145821965
%N A367473 Expansion of e.g.f. 1 / (4 - 3 * exp(x))^3.
%F A367473 a(n) = (1/2) * Sum_{k=0..n} 3^k * (k+2)! * Stirling2(n,k).
%F A367473 a(0) = 1; a(n) = 3*Sum_{k=1..n} (2*k/n + 1) * binomial(n,k) * a(n-k).
%F A367473 a(0) = 1; a(n) = 9*a(n-1) - 4*Sum_{k=1..n-1} (-1)^k * binomial(n-1,k) * a(n-k).
%o A367473 (PARI) a(n) = sum(k=0, n, 3^k*(k+2)!*stirling(n, k, 2))/2;
%Y A367473 Cf. A032033, A367472.
%Y A367473 Cf. A226515, A367471.
%K A367473 nonn
%O A367473 0,2
%A A367473 _Seiichi Manyama_, Nov 19 2023