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 A377458 #37 Dec 13 2024 09:40:25
%S A377458 1,1,1,4,7,29,61,256,596,2507,6247,26197,68652,286232,780508,3231060,
%T A377458 9102590,37392935,108279767,441342883,1308552478,5292781266,
%U A377458 16018989626,64315663716,198213843417,790252270626,2474924176566,9802205324516,31142246753638
%N A377458 G.f. A(x) satisfies A(x) = 1 + x/A(x)^2 * (1 - A(x) + A(x)^4).
%F A377458 a(n) = (1/n) * Sum_{k=0..n} (-1)^k * binomial(n,k) * binomial(2*n-4*k,n-k-1) for n > 0.
%o A377458 (PARI) a(n) = if(n==0, 1, sum(k=0, n, (-1)^k*binomial(n, k)*binomial(2*n-4*k, n-k-1))/n);
%Y A377458 Cf. A317133, A364759, A377706, A378958, A378920.
%Y A377458 Cf. A371891.
%K A377458 nonn
%O A377458 0,4
%A A377458 _Seiichi Manyama_, Dec 12 2024