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 A380727 #8 Jan 31 2025 09:25:45
%S A380727 1,2,31,988,48533,3240016,274099723,28110919712,3389978711785,
%T A380727 470124480093184,73718009095023191,12897488652935429632,
%U A380727 2490884805057416903869,526368104133213244928000,120811269372167469194820547,29928528196949304888405323776,7959458742917430589011715194833
%N A380727 E.g.f. A(x) satisfies A(x) = exp(x * A(x)^3 / (1 - x*A(x)^3)) / (1 - x*A(x)^3).
%F A380727 a(n) = n! * Sum_{k=0..n} (3*n+1)^(k-1) * binomial(4*n,n-k)/k!.
%o A380727 (PARI) a(n) = n!*sum(k=0, n, (3*n+1)^(k-1)*binomial(4*n, n-k)/k!);
%Y A380727 Cf. A380663, A380726.
%Y A380727 Cf. A380724.
%K A380727 nonn
%O A380727 0,2
%A A380727 _Seiichi Manyama_, Jan 31 2025