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 A371272 #9 Mar 17 2024 04:08:31
%S A371272 1,0,2,3,148,905,40506,542437,25080392,562677201,28058678110,
%T A371272 908452740701,49777760550684,2120072013408505,128583516119137730,
%U A371272 6778703037793746165,455574282215526201616,28520235381763443992993,2118889776612629769160518
%N A371272 E.g.f. satisfies A(x) = 1 + x*A(x)^3 * (exp(x*A(x)^3) - 1).
%F A371272 a(n) = n! * (3*n)! * Sum_{k=0..floor(n/2)} Stirling2(n-k,k)/( (n-k)! * (3*n-k+1)! ).
%o A371272 (PARI) a(n) = n!*(3*n)!*sum(k=0, n\2, stirling(n-k, k, 2)/((n-k)!*(3*n-k+1)!));
%Y A371272 Cf. A371231.
%K A371272 nonn
%O A371272 0,3
%A A371272 _Seiichi Manyama_, Mar 16 2024