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 A369488 #8 Jan 24 2024 08:00:16
%S A369488 1,1,5,20,101,522,2860,16115,93200,549286,3288633,19942666,122243210,
%T A369488 756188245,4714629930,29595888020,186903732003,1186606564605,
%U A369488 7569137651545,48486925091800,311788811682494,2011863788481296,13022795014568290,84539592912435990
%N A369488 Expansion of (1/x) * Series_Reversion( x / (1-x)^2 * (1-x-x^2)^3 ).
%H A369488 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369488 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(3*n+k+2,k) * binomial(2*n-k,n-2*k).
%o A369488 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/(1-x)^2*(1-x-x^2)^3)/x)
%o A369488 (PARI) a(n, s=2, t=3, u=2) = 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 A369488 Cf. A369487.
%K A369488 nonn
%O A369488 0,3
%A A369488 _Seiichi Manyama_, Jan 24 2024