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 A188622 #31 Sep 08 2022 08:45:56
%S A188622 1,3,10,34,118,418,1508,5524,20486,76722,289580,1099836,4198396,
%T A188622 16093236,61902472,238805864,923574598,3579675026,13900879132,
%U A188622 54071886764,210645038548,821701422716,3209243934712,12547819633304,49109812222108,192382627198868
%N A188622 Row sums of the Riordan matrix (1/sqrt(1-4*x), x/(1-x)) (A187888).
%H A188622 G. C. Greubel, <a href="/A188622/b188622.txt">Table of n, a(n) for n = 0..1000</a> (terms 0..100 from Vincenzo Librandi)
%F A188622 D-finite with recurrence: (n+3)*a(n+3) - (7*n+17)*a(n+2) + 2*(7*n+12)*a(n+1) - 4*(2*n+1)*a(n) = 0.
%F A188622 G.f.: (1-x)/((1-2*x)*sqrt(1-4*x)).
%t A188622 CoefficientList[Series[(1-x)/((1-2x)Sqrt[1-4x]),{x,0,30}],x] (* _Harvey P. Dale_, Oct 25 2016 *)
%o A188622 (Maxima) a(n):=at(diff((1-x)/((1-2*x)*sqrt(1-4*x)),x,n),x=0)/n!;
%o A188622 makelist(a(n),n,0,24);
%o A188622 (PARI) x='x+O('x^30); Vec((1-x)/((1-2*x)*sqrt(1-4*x))) \\ _G. C. Greubel_, Nov 01 2018
%o A188622 (Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); Coefficients(R!((1-x)/((1-2*x)*Sqrt(1-4*x)))); // _G. C. Greubel_, Nov 01 2018
%Y A188622 Cf. A187888
%K A188622 nonn,easy
%O A188622 0,2
%A A188622 _Emanuele Munarini_, Apr 06 2011
%E A188622 More terms from _Harvey P. Dale_, Oct 25 2016