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 A369477 #12 Jan 24 2024 05:56:00
%S A369477 1,3,14,77,464,2964,19717,135131,947549,6765642,49022225,359545750,
%T A369477 2664127354,19913283809,149968276974,1136856855549,8668000962927,
%U A369477 66428474900907,511414514214628,3953420853213504,30674783555852576,238808419235022293,1864869207177530320
%N A369477 Expansion of (1/x) * Series_Reversion( x / ((1+x) * (1+x+x^2)^2) ).
%H A369477 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369477 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(2*n+2,k) * binomial(3*n-k+3,n-2*k).
%o A369477 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)*(1+x+x^2)^2))/x)
%o A369477 (PARI) a(n, s=2, t=2, u=1) = sum(k=0, n\s, binomial(t*(n+1), k)*binomial((t+u)*(n+1)-k, n-s*k))/(n+1);
%Y A369477 Cf. A106228, A369479.
%Y A369477 Cf. A143927, A369478.
%Y A369477 Cf. A369440.
%K A369477 nonn
%O A369477 0,2
%A A369477 _Seiichi Manyama_, Jan 23 2024