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 A369478 #14 Jan 24 2024 05:56:19
%S A369478 1,4,24,170,1320,10868,93197,823484,7445184,68545882,640446224,
%T A369478 6057249180,57878746750,557903174040,5418441862824,52971933934834,
%U A369478 520869559359424,5147999004530720,51113415228327827,509583784051748692,5099262428810825568
%N A369478 Expansion of (1/x) * Series_Reversion( x / ((1+x)^2 * (1+x+x^2)^2) ).
%H A369478 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369478 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(2*n+2,k) * binomial(4*n-k+4,n-2*k).
%o A369478 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^2*(1+x+x^2)^2))/x)
%o A369478 (PARI) a(n, s=2, t=2, u=2) = sum(k=0, n\s, binomial(t*(n+1), k)*binomial((t+u)*(n+1)-k, n-s*k))/(n+1);
%Y A369478 Cf. A219537, A369480.
%Y A369478 Cf. A143927, A369477.
%Y A369478 Cf. A369441.
%K A369478 nonn
%O A369478 0,2
%A A369478 _Seiichi Manyama_, Jan 23 2024