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 A380753 #9 Feb 01 2025 08:42:11
%S A380753 1,3,47,1453,68349,4344751,348936139,33912469305,3871084443641,
%T A380753 507765120717691,75265926888996711,12443096536067016997,
%U A380753 2270083842550815380725,453042725968243823206887,98183026886745981671902979,22962952582930039784948279281,5764815614414943166224203759601
%N A380753 E.g.f. A(x) satisfies A(x) = exp(x * A(x)^2) / (1 - x * A(x)^2)^2.
%F A380753 a(n) = n! * Sum_{k=0..n} (2*n+1)^(k-1) * binomial(5*n-k+1,n-k)/k!.
%o A380753 (PARI) a(n) = n!*sum(k=0, n, (2*n+1)^(k-1)*binomial(5*n-k+1, n-k)/k!);
%Y A380753 Cf. A377745, A380752.
%Y A380753 Cf. A380723.
%K A380753 nonn
%O A380753 0,2
%A A380753 _Seiichi Manyama_, Feb 01 2025