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 A134759 #11 May 28 2024 18:28:30
%S A134759 1,2,9,36,135,498,1841,6856,25731,97230,369501,1410852,5408299,
%T A134759 20801186,80233185,310235024,1202160763,4667212422,18150270581,
%U A134759 70690527580,275693057619,1076515748858,4208197927417,16466861455176,64495207366175,252821212875478
%N A134759 a(n) = 2*A000984(n) - (n+1).
%H A134759 G. C. Greubel, <a href="/A134759/b134759.txt">Table of n, a(n) for n = 0..1000</a>
%F A134759 From _G. C. Greubel_, May 28 2024: (Start)
%F A134759 a(n) = (n+1)*(2*A000108(n) - 1).
%F A134759 a(n) = (2*(2*n-1)*a(n-1) + 3*n*(n-1))/n.
%F A134759 G.f.: 2/sqrt(1-4*x) - 1/(1-x)^2.
%F A134759 E.g.f.: 2*exp(2*x)*BesselI(0, 2*x) - (1+x)*exp(x). (End)
%t A134759 Table[2 Binomial[2n,n]-n-1,{n,0,30}] (* _Harvey P. Dale_, Aug 07 2023 *)
%o A134759 (Magma) [(n+1)*(2*Catalan(n)-1): n in [0..40]]; // _G. C. Greubel_, May 28 2024
%o A134759 (SageMath) [2*binomial(2*n,n) -(n+1) for n in range(41)] # _G. C. Greubel_, May 28 2024
%Y A134759 Cf. A000108, A000984, A134758, A134760, A134761, A134762, A134763, A134770, A134771.
%K A134759 nonn
%O A134759 0,2
%A A134759 _Gary W. Adamson_, Nov 09 2007
%E A134759 More terms from _Harvey P. Dale_, Aug 07 2023