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 A267883 #11 Jun 24 2025 12:30:37
%S A267883 0,3,2,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%T A267883 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%U A267883 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N A267883 Number of OFF (white) cells in the n-th iteration of the "Rule 233" elementary cellular automaton starting with a single ON (black) cell.
%D A267883 S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.
%H A267883 Robert Price, <a href="/A267883/b267883.txt">Table of n, a(n) for n = 0..1000</a>
%H A267883 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ElementaryCellularAutomaton.html">Elementary Cellular Automaton</a>
%H A267883 S. Wolfram, <a href="http://wolframscience.com/">A New Kind of Science</a>
%H A267883 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>
%H A267883 <a href="https://oeis.org/wiki/Index_to_Elementary_Cellular_Automata">Index to Elementary Cellular Automata</a>
%t A267883 rule=233; 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 *) nbc=Table[Total[catri[[k]]],{k,1,rows}]; (* Number of Black cells in stage n *) Table[Length[catri[[k]]]-nbc[[k]],{k,1,rows}] (* Number of White cells in stage n *)
%Y A267883 Cf. A267868, A130713.
%K A267883 nonn,easy
%O A267883 0,2
%A A267883 _Robert Price_, Jan 21 2016