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 A380674 #9 Jan 30 2025 11:23:40
%S A380674 1,3,25,370,8097,237096,8733601,388380000,20253654945,1212334652800,
%T A380674 81937521020841,6172429566120192,512850795552978625,
%U A380674 46594245206418954240,4595466275857015549425,488993161791784338804736,55839856392986843905585089,6811561624203525171739852800
%N A380674 Expansion of e.g.f. (1/x) * Series_Reversion( x * (1 - x)^2 * exp(-x * (1 - x)^2) ).
%H A380674 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A380674 E.g.f. A(x) satisfies A(x) = exp(x * A(x) * (1 - x*A(x))^2)/(1 - x*A(x))^2.
%F A380674 a(n) = n! * Sum_{k=0..n} (n+1)^(k-1) * binomial(3*n-3*k+1,n-k)/k!.
%o A380674 (PARI) a(n) = n!*sum(k=0, n, (n+1)^(k-1)*binomial(3*n-3*k+1, n-k)/k!);
%Y A380674 Cf. A377832, A380665, A380666, A380675.
%K A380674 nonn
%O A380674 0,2
%A A380674 _Seiichi Manyama_, Jan 30 2025