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Number of OFF (white) cells in the n-th iteration of the "Rule 75" elementary cellular automaton starting with a single ON (black) cell.
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%I #7 Jan 09 2016 15:11:28

%S 0,2,2,3,4,6,8,6,10,9,13,9,15,10,19,13,20,16,23,15,24,16,30,19,30,18,

%T 39,16,35,24,37,27,39,27,45,21,46,33,45,31,51,26,56,31,53,33,55,37,63,

%U 29,69,35,60,44,68,38,70,41,71,37,78,38,76,48,83,41,90

%N Number of OFF (white) cells in the n-th iteration of the "Rule 75" elementary cellular automaton starting with a single ON (black) cell.

%D S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.

%H Robert Price, <a href="/A266900/b266900.txt">Table of n, a(n) for n = 0..1000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ElementaryCellularAutomaton.html">Elementary Cellular Automaton</a>

%H S. Wolfram, <a href="http://wolframscience.com/">A New Kind of Science</a>

%H <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>

%H <a href="https://oeis.org/wiki/Index_to_Elementary_Cellular_Automata">Index to Elementary Cellular Automata</a>

%t rule=75; 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 Cf. A266892.

%K nonn,easy

%O 0,2

%A _Robert Price_, Jan 05 2016