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 A173711 #17 Sep 08 2022 08:45:50
%S A173711 0,0,0,0,0,0,1,1,2,2,2,2,2,2,3,3,4,4,4,4,4,4,5,5,6,6,6,6,6,6,7,7,8,8,
%T A173711 8,8,8,8,9,9,10,10,10,10,10,10,11,11,12,12,12,12,12,12,13,13,14,14,14,
%U A173711 14,14,14,15,15,16,16,16,16,16,16,17,17
%N A173711 Nonnegative integers, six even followed by two odd.
%H A173711 G. C. Greubel, <a href="/A173711/b173711.txt">Table of n, a(n) for n = 0..1000</a>
%H A173711 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1,-1,1,1,-1).
%F A173711 a(n) = A180969(3,n) + A180969(3,n+2).
%F A173711 G.f.: x^6 / ((x+1)*(x^4+1)*(x-1)^2).
%F A173711 a(n) = a(n-1) + a(n-2) - a(n-3) - a(n-4) + a(n-5) + a(n-6) - a(n-7). - _G. C. Greubel_, Nov 23 2016
%t A173711 LinearRecurrence[{1,1,-1,-1,1,1,-1},{0,0,0,0,0,0,1},50] (* _G. C. Greubel_, Nov 23 2016 *)
%t A173711 CoefficientList[Series[x^6 / ((x + 1) (x^4 + 1) (x - 1)^2), {x, 0, 100}], x] (* _Vincenzo Librandi_, Nov 24 2016 *)
%t A173711 Table[If[EvenQ[n],PadRight[{},6,n],{n,n}],{n,0,20}]//Flatten (* _Harvey P. Dale_, Nov 07 2020 *)
%o A173711 (Magma) I:=[0,0,0,0,0,0,1]; [n le 7 select I[n] else Self(n-1) + Self(n-2) - Self(n-3)-Self(n-4)+Self(n-5)+Self(n-6)-Self(n-7): n in [1..80]]; // _Vincenzo Librandi_, Nov 24 2016
%K A173711 easy,nonn
%O A173711 0,9
%A A173711 _Adriano Caroli_, Nov 25 2010