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 A369505 #8 Jan 25 2024 07:49:59
%S A369505 1,8,86,1066,14361,204314,3020745,45955442,714723588,11312450432,
%T A369505 181625888244,2950848879096,48423670556100,801454908292020,
%U A369505 13363137183238881,224253208102065664,3784736105491395780,64197997357038408976,1093863031541592651003
%N A369505 Expansion of (1/x) * Series_Reversion( x / ((1+x)^3+x)^2 ).
%H A369505 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369505 a(n) = (1/(n+1)) * Sum_{k=0..n} binomial(2*n+2,k) * binomial(6*n-3*k+6,n-k).
%o A369505 (PARI) my(N=20, x='x+O('x^N)); Vec(serreverse(x/((1+x)^3+x)^2)/x)
%o A369505 (PARI) a(n) = sum(k=0, n, binomial(2*n+2, k)*binomial(6*n-3*k+6, n-k))/(n+1);
%Y A369505 Cf. A003645, A369502.
%K A369505 nonn
%O A369505 0,2
%A A369505 _Seiichi Manyama_, Jan 25 2024