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 A360310 #12 Feb 03 2023 08:17:42
%S A360310 1,0,0,0,2,2,2,2,8,14,20,26,52,98,164,250,426,762,1328,2194,3682,6366,
%T A360310 11072,18878,32038,54906,94860,163226,279634,479806,826776,1425542,
%U A360310 2454020,4223170,7279164,12560466,21671314,37381714,64512676,111414042
%N A360310 a(n) = Sum_{k=0..floor(n/4)} binomial(n-1-3*k,n-4*k) * binomial(2*k,k).
%F A360310 G.f.: 1 / sqrt(1-4*x^4/(1-x)).
%F A360310 n*a(n) = 2*(n-1)*a(n-1) - (n-2)*a(n-2) + 2*(2*n-4)*a(n-4) - 2*(2*n-7)*a(n-5).
%o A360310 (PARI) a(n) = sum(k=0, n\4, binomial(n-1-3*k, n-4*k)*binomial(2*k, k));
%o A360310 (PARI) my(N=40, x='x+O('x^N)); Vec(1/sqrt(1-4*x^4/(1-x)))
%Y A360310 Cf. A026585, A360309.
%Y A360310 Cf. A360292, A360315.
%K A360310 nonn
%O A360310 0,5
%A A360310 _Seiichi Manyama_, Feb 03 2023