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 A026849 #15 Sep 08 2022 08:44:49
%S A026849 1,9,56,300,1487,7041,32381,146017,649395,2859231,12494914,54291912,
%T A026849 234860677,1012433965,4352210327,18666918033,79916230409,341615895659,
%U A026849 1458457275715,6220016154525,26503542364381,112847001503099,480173686483581
%N A026849 a(n) = T(2n,n-3), T given by A026736.
%C A026849 Is this the same as A026846 and A026842? - _R. J. Mathar_, Oct 23 2008
%C A026849 Column k=8 of triangle A236830. - _Philippe Deléham_, Feb 02 2014
%H A026849 G. C. Greubel, <a href="/A026849/b026849.txt">Table of n, a(n) for n = 3..1000</a>
%F A026849 a(n) = A026842(n) = A026846(n). - _Philippe Deléham_, Feb 02 2014
%F A026849 G.f.: (x^3*C(x)^8)/(1-x*C(x)^3) where C(x) is the g.f. of A000108. - _Philippe Deléham_, Feb 02 2014
%t A026849 CoefficientList[Series[(1-Sqrt[1-4*x])^8/(32*x^3*(8*x^2 -(1-Sqrt[1-4*x])^3 )), {x,0,30}], x] (* _G. C. Greubel_, Jul 17 2019 *)
%o A026849 (PARI) my(x='x+O('x^30)); Vec((1-sqrt(1-4*x))^8/(32*x^3*(8*x^2 -(1-sqrt(1-4*x))^3 ))) \\ _G. C. Greubel_, Jul 17 2019
%o A026849 (Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( (1-Sqrt(1-4*x))^8/(32*x^3*(8*x^2 -(1-Sqrt(1-4*x))^3 )) )); // _G. C. Greubel_, Jul 17 2019
%o A026849 (Sage) a=((1-sqrt(1-4*x))^8/(32*x^3*(8*x^2 -(1-sqrt(1-4*x))^3 ))).series(x, 30).coefficients(x, sparse=False); a[3:] # _G. C. Greubel_, Jul 17 2019
%Y A026849 Cf. A236830.
%K A026849 nonn
%O A026849 3,2
%A A026849 _Clark Kimberling_