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 A369581 #11 Jan 27 2024 10:31:33
%S A369581 1,1,1,1,2,4,7,11,20,40,79,147,278,550,1110,2204,4352,8708,17689,
%T A369581 35971,72933,148271,303582,624132,1283898,2643354,5458457,11306443,
%U A369581 23460067,48727689,101363663,211262307,441026328,921743772,1928573045,4040272335,8474803721
%N A369581 Expansion of (1/x) * Series_Reversion( x / (1+x+x^4/(1+x)^2) ).
%H A369581 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369581 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} binomial(n+1,k) * binomial(n-3*k+1,n-4*k).
%o A369581 (PARI) my(N=40, x='x+O('x^N)); Vec(serreverse(x/(1+x+x^4/(1+x)^2))/x)
%o A369581 (PARI) a(n) = sum(k=0, n\4, binomial(n+1, k)*binomial(n-3*k+1, n-4*k))/(n+1);
%Y A369581 Cf. A367414.
%K A369581 nonn
%O A369581 0,5
%A A369581 _Seiichi Manyama_, Jan 26 2024