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 A369483 #11 Jan 24 2024 05:57:36
%S A369483 1,2,5,16,60,242,1014,4370,19278,86678,395751,1829742,8549100,
%T A369483 40302810,191469165,915751966,4405727502,21307102900,103526683797,
%U A369483 505118705078,2473833623696,12157124607612,59929746189165,296271556144028,1468494529164194,7296261411708962
%N A369483 Expansion of (1/x) * Series_Reversion( x / (1+x+x^3)^2 ).
%H A369483 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369483 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(2*n+2,k) * binomial(2*n-k+2,n-3*k).
%o A369483 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/(1+x+x^3)^2)/x)
%o A369483 (PARI) a(n, s=3, t=2, u=0) = sum(k=0, n\s, binomial(t*(n+1), k)*binomial((t+u)*(n+1)-k, n-s*k))/(n+1);
%Y A369483 Cf. A369484, A369485.
%Y A369483 Cf. A071879.
%K A369483 nonn
%O A369483 0,2
%A A369483 _Seiichi Manyama_, Jan 23 2024