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 A366055 #8 Sep 27 2023 10:06:22
%S A366055 1,2,7,30,144,741,3996,22287,127494,743919,4410255,26489073,160843708,
%T A366055 985729010,6089215057,37875775533,237021929322,1491204370335,
%U A366055 9426547131330,59843910602283,381378377720469,2438954925930558,15646857920046108
%N A366055 Expansion of (1/x) * Series_Reversion( x*(1-x)^3/(1-x+x^4) ).
%F A366055 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} binomial(n+1,k) * binomial(3*n-3*k+1,n-4*k).
%o A366055 (PARI) a(n) = sum(k=0, n\4, binomial(n+1, k)*binomial(3*n-3*k+1, n-4*k))/(n+1);
%Y A366055 Cf. A215341, A366054, A366056.
%K A366055 nonn
%O A366055 0,2
%A A366055 _Seiichi Manyama_, Sep 27 2023