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 A192811 #27 Sep 08 2022 08:45:58
%S A192811 0,0,1,7,37,183,893,4351,21205,103367,503917,2456655,11976517,
%T A192811 58387095,284644701,1387679903,6765119669,32980836455,160785858381,
%U A192811 783851928559,3821379890981,18629722961207,90822317465149,442770585849407
%N A192811 a(n) = A192809(n)/2.
%H A192811 G. C. Greubel, <a href="/A192811/b192811.txt">Table of n, a(n) for n = 0..1000</a>
%H A192811 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (7,-12,8).
%F A192811 a(n) = 7*a(n-1) - 12*a(n-2) + 8*a(n-3).
%F A192811 G.f.: x^2/(1-7*x+12*x^2-8*x^3). - _Colin Barker_, Jul 26 2012
%t A192811 (See A192808.)
%t A192811 LinearRecurrence[{7,-12,8},{0,0,1},30] (* _Harvey P. Dale_, Dec 06 2018 *)
%o A192811 (PARI) my(x='x+O('x^30)); concat([0,0], Vec(x^2/(1-7*x+12*x^2-8*x^3))) \\ _G. C. Greubel_, Jan 03 2019
%o A192811 (Magma) m:=30; R<x>:=PowerSeriesRing(Integers(), m); [0,0] cat Coefficients(R!( x^2/(1-7*x+12*x^2-8*x^3) )); // _G. C. Greubel_, Jan 03 2019
%o A192811 (Sage) (x^2/(1-7*x+12*x^2-8*x^3)).series(x, 30).coefficients(x, sparse=False) # _G. C. Greubel_, Jan 03 2019
%o A192811 (GAP) a:=[0,0,1];; for n in [4..25] do a[n]:=7*a[n-1]-12*a[n-2]+8*a[n-3]; od; Print(a); # _Muniru A Asiru_, Jan 03 2019
%Y A192811 Cf. A192232, A192744, A192809.
%K A192811 nonn,easy
%O A192811 0,4
%A A192811 _Clark Kimberling_, Jul 10 2011
%E A192811 Name corrected by _Colin Barker_, Jul 26 2012