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 A372383 #9 Apr 29 2024 09:10:36
%S A372383 1,1,5,13,63,225,1069,4425,21008,93927,449574,2099993,10161845,
%T A372383 48761421,238544091,1165258909,5756929854,28480358700,141911407403,
%U A372383 708766944499,3557401656125,17900413391858,90401732441880,457657822713177,2323507912981800,11822283300379509
%N A372383 Expansion of (1/x) * Series_Reversion( x * (1+x)^3 / (1+x+x^2)^4 ).
%H A372383 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A372383 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(4*n+4,k) * binomial(n-k+1,n-2*k).
%o A372383 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1+x)^3/(1+x+x^2)^4)/x)
%o A372383 (PARI) a(n, s=2, t=4, u=-3) = sum(k=0, n\s, binomial(t*(n+1), k)*binomial((t+u)*(n+1)-k, n-s*k))/(n+1);
%Y A372383 Cf. A372382.
%K A372383 nonn
%O A372383 0,3
%A A372383 _Seiichi Manyama_, Apr 29 2024