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 A366240 #9 Oct 05 2023 08:34:57
%S A366240 1,2,9,60,432,3378,27792,237122,2079132,18620709,169614960,1566540573,
%T A366240 14635978998,138080055192,1313596636812,12587218990644,
%U A366240 121378106852988,1176981533610012,11469587139406515,112265849283068877,1103256200355696855
%N A366240 G.f. A(x) satisfies A(x) = 1 + x + x*(1 + x)^3*A(x)^3.
%F A366240 a(n) = Sum_{k=0..n} binomial(5*k+1,n-k) * binomial(3*k,k)/(2*k+1).
%o A366240 (PARI) a(n) = sum(k=0, n, binomial(5*k+1, n-k)*binomial(3*k, k)/(2*k+1));
%Y A366240 Cf. A364336, A366239, A366241.
%K A366240 nonn
%O A366240 0,2
%A A366240 _Seiichi Manyama_, Oct 05 2023