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 A368966 #19 Jan 13 2024 10:45:29
%S A368966 1,3,15,93,644,4769,36953,295867,2428373,20322566,172759032,
%T A368966 1487632887,12948891408,113748663495,1007117650350,8978151790011,
%U A368966 80519598139947,725976573163011,6576546244337046,59829384514916820,546375444906314661,5006934930385254672
%N A368966 Expansion of (1/x) * Series_Reversion( x * (1-x) * (1-x-x^3)^2 ).
%H A368966 Seiichi Manyama, <a href="/A368966/b368966.txt">Table of n, a(n) for n = 0..1000</a>
%H A368966 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A368966 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(2*n+k+1,k) * binomial(4*n-2*k+2,n-3*k).
%o A368966 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-x)*(1-x-x^3)^2)/x)
%o A368966 (PARI) a(n, s=3, t=2, u=1) = sum(k=0, n\s, binomial(t*(n+1)+k-1, k)*binomial((t+u+1)*(n+1)-(s-1)*k-2, n-s*k))/(n+1);
%Y A368966 Cf. A368962, A368968.
%Y A368966 Cf. A368965.
%K A368966 nonn
%O A368966 0,2
%A A368966 _Seiichi Manyama_, Jan 10 2024