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 A266680 #34 Feb 16 2025 08:33:28
%S A266680 1,11,110,1101,11011,110111,1101111,11011111,110111111,1101111111,
%T A266680 11011111111,110111111111,1101111111111,11011111111111,
%U A266680 110111111111111,1101111111111111,11011111111111111,110111111111111111,1101111111111111111,11011111111111111111
%N A266680 Binary representation of the middle column of the "Rule 175" elementary cellular automaton starting with a single ON (black) cell.
%D A266680 S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.
%H A266680 Robert Price, <a href="/A266680/b266680.txt">Table of n, a(n) for n = 0..1000</a>
%H A266680 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ElementaryCellularAutomaton.html">Elementary Cellular Automaton</a>
%H A266680 S. Wolfram, <a href="http://wolframscience.com/">A New Kind of Science</a>
%H A266680 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>
%H A266680 <a href="https://oeis.org/wiki/Index_to_Elementary_Cellular_Automata">Index to Elementary Cellular Automata</a>
%F A266680 Conjectures from _Colin Barker_, Jan 19 2016 and Apr 18 2019: (Start)
%F A266680 a(n) = 11*a(n-1) - 10*a(n-2) for n > 3.
%F A266680 G.f.: (1-x^2+x^3) / ((1-x)*(1-10*x)).
%F A266680 (End)
%t A266680 rule=175; rows=20; ca=CellularAutomaton[rule,{{1},0},rows-1,{All,All}]; (* Start with single black cell *) catri=Table[Take[ca[[k]],{rows-k+1,rows+k-1}],{k,1,rows}]; (* truncated list of each row *) mc=Table[catri[[k]][[k]],{k,1,rows}]; (* keep only middle cell from each row *) Table[FromDigits[Take[mc,k]],{k,1,rows}] (* binary representation of middle column *)
%Y A266680 Cf. A265186, A266678, A267604.
%K A266680 nonn,easy
%O A266680 0,2
%A A266680 _Robert Price_, Jan 18 2016