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 A026852 #15 Sep 08 2022 08:44:49
%S A026852 1,8,45,221,1016,4506,19572,83950,357310,1513513,6392134,26948764,
%T A026852 113500985,477801129,2011058681,8464967333,35637556603,150075181365,
%U A026852 632191803847,2664023530675,11229995113561,47355649431833,199760722776165
%N A026852 a(n) = T(2n,n+3), T given by A026736.
%H A026852 G. C. Greubel, <a href="/A026852/b026852.txt">Table of n, a(n) for n = 3..1000</a>
%F A026852 G.f.: x^3*C(x)^7/(1 - x/Sqrt(1-4*x)) = x^3*(1-2*x*C(x))*C(x)^9/(1-x*C(x)^3), where C(x) is the g.f. of A000108. - _G. C. Greubel_, Jul 17 2019
%F A026852 a(n) ~ (2 + sqrt(5))^(n+3) * (3 - sqrt(5))^7 / (128*sqrt(5)). - _Vaclav Kotesovec_, Jul 18 2019
%t A026852 Drop[CoefficientList[Series[Sqrt[1-4*x]*(1-Sqrt[1-4*x])^9/(64*x^4*(8*x^2 -(1-Sqrt[1-4*x])^3)), {x, 0, 40}], x], 3] (* _G. C. Greubel_, Jul 17 2019 *)
%o A026852 (PARI) my(x='x+O('x^40)); Vec(sqrt(1-4*x)*(1-sqrt(1-4*x))^9/(64*x^4*(8*x^2 -(1 - sqrt(1-4*x))^3 ))) \\ _G. C. Greubel_, Jul 17 2019
%o A026852 (Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( Sqrt(1-4*x)*(1-Sqrt(1-4*x))^9/(64*x^4*(8*x^2 -(1-Sqrt(1-4*x))^3 )) )); // _G. C. Greubel_, Jul 17 2019
%o A026852 (Sage) a=(sqrt(1-4*x)*(1-sqrt(1-4*x))^9/(64*x^4*(8*x^2 -(1-sqrt(1-4*x))^3 ))).series(x, 45).coefficients(x, sparse=False); a[3:40] # _G. C. Greubel_, Jul 17 2019
%Y A026852 Cf. A000108, A026736.
%K A026852 nonn
%O A026852 3,2
%A A026852 _Clark Kimberling_