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 A365724 #11 Sep 17 2023 10:11:03
%S A365724 1,0,0,1,1,0,3,7,4,12,45,55,77,286,546,728,1960,4760,7548,15504,39729,
%T A365724 75582,140448,336490,723327,1366200,2992990,6758895,13522275,28094040,
%U A365724 63183315,133231800,273896532,600805296,1305229332,2720740792,5843241088,12797739672
%N A365724 G.f. satisfies A(x) = 1 + x^3*A(x)^3*(1 + x*A(x)).
%F A365724 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(k,n-3*k) * binomial(n+1,k).
%o A365724 (PARI) a(n) = sum(k=0, n\3, binomial(k, n-3*k)*binomial(n+1, k))/(n+1);
%Y A365724 Cf. A308616, A365723, A365725, A365726.
%Y A365724 Cf. A001005, A001006, A365730.
%Y A365724 Cf. A114997.
%K A365724 nonn
%O A365724 0,7
%A A365724 _Seiichi Manyama_, Sep 17 2023