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 A366645 #9 Oct 15 2023 09:26:00
%S A366645 1,0,0,1,4,10,24,67,200,586,1704,5049,15232,46284,141240,433696,
%T A366645 1340500,4164830,12993792,40697472,127941300,403561902,1276763096,
%U A366645 4050430502,12882398456,41068966204,131211997496,420056152498,1347272602056,4328764460928,13931034024536
%N A366645 G.f. A(x) satisfies A(x) = 1 + x^3 * (A(x) / (1 - x))^4.
%F A366645 a(n) = Sum_{k=0..floor(n/3)} binomial(n+k-1,n-3*k) * binomial(4*k,k) / (3*k+1).
%o A366645 (PARI) a(n) = sum(k=0, n\3, binomial(n+k-1, n-3*k)*binomial(4*k, k)/(3*k+1));
%Y A366645 Partial sums give A215340.
%Y A366645 Cf. A213336, A364410, A366646.
%K A366645 nonn
%O A366645 0,5
%A A366645 _Seiichi Manyama_, Oct 15 2023