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 A376811 #10 Oct 05 2024 02:49:18
%S A376811 1,2,6,20,74,276,1044,3998,15450,60128,235332,925332,3652508,14464490,
%T A376811 57442074,228670140,912239782,3646027752,14596600800,58523194734,
%U A376811 234954663396,944418233612,3800327339532,15307785490560,61716607166724,249033637247898,1005661821858414
%N A376811 Expansion of 1/sqrt(1 - 4*x/(1 - x^3)^2).
%F A376811 a(n) = Sum_{k=0..floor(n/3)} binomial(2*n-5*k-1,k) * binomial(2*n-6*k,n-3*k).
%o A376811 (PARI) my(N=30, x='x+O('x^N)); Vec(1/sqrt(1-4*x/(1-x^3)^2))
%o A376811 (PARI) a(n) = sum(k=0, n\3, binomial(2*n-5*k-1, k)*binomial(2*n-6*k, n-3*k));
%Y A376811 Cf. A110170, A376810.
%Y A376811 Cf. A376791.
%K A376811 nonn
%O A376811 0,2
%A A376811 _Seiichi Manyama_, Oct 04 2024