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 A380765 #12 Feb 03 2025 11:07:51
%S A380765 1,3,19,241,4853,131601,4466875,182546421,8739580841,480023587297,
%T A380765 29759608788551,2055884656223949,156623317577663293,
%U A380765 13045653418406432721,1179479817324874518419,115042876530398843323621,12041278143223263581774417,1346252625757920938545507521
%N A380765 E.g.f. A(x) satisfies A(x) = exp(x * (1 - x*A(x))^2) / (1 - x*A(x))^2.
%F A380765 a(n) = n! * Sum_{k=0..n} (n-k+1)^(k-1) * binomial(3*n-5*k+1,n-k)/k!.
%o A380765 (PARI) a(n, q=1, r=1, s=0, t=-2, u=2) = q*n!*sum(k=0, n, (r*n+(s-r)*k+q)^(k-1)*binomial((r*u+1)*n+((s-r)*u+t-1)*k+q*u-1, n-k)/k!);
%Y A380765 Cf. A377742, A380764.
%K A380765 nonn
%O A380765 0,2
%A A380765 _Seiichi Manyama_, Feb 01 2025