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 A080354 #5 Dec 08 2019 13:34:49
%S A080354 2,2,2,1,2,1,2,1,2,1,1,2,1,1,2,1,1,2,1,1,1,2,1,1,1,2,1,1,1,2,1,1,1,1,
%T A080354 2,1,1,1,1,2,1,1,1,1,2,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1,1,1,
%U A080354 1,2,1,1,1,1,1,1,2,1,1,1,1,1,1,2,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1
%N A080354 First differences of A080353.
%F A080354 Runs are 2^2, (2 1)^3, (2 1 1)^3, (2 1 1 1)^3, ...
%t A080354 Most[Table[#,3]&/@Table[PadRight[{2},n,1],{n,10}]//Flatten] (* _Harvey P. Dale_, Dec 08 2019 *)
%K A080354 nonn
%O A080354 0,1
%A A080354 _N. J. A. Sloane_, Mar 20 2003