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A269716
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Number of active (ON,black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 22", based on the 5-celled von Neumann neighborhood.
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0
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1, 5, 20, 88, 368, 1504, 6080, 24448, 98048, 392704, 1571840, 6289408, 25161728, 100655104, 402636800, 1610579968
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OFFSET
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0,2
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COMMENTS
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Initialized with a single black (ON) cell at stage zero.
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REFERENCES
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S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 170.
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LINKS
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FORMULA
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a(n) = 2^(n-1)*(3*2^n-2) for n>1.
a(n) = 6*a(n-1)-8*a(n-2) for n>3.
G.f.: (1+2*x)*(1-3*x+4*x^2) / ((1-2*x)*(1-4*x)).
(End)
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MATHEMATICA
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rule=22; stages=300;
ca=CellularAutomaton[{rule, {2, {{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}}, {1, 1}}, {{{1}}, 0}, stages]; (* Start with single black cell *)
on=Map[Function[Apply[Plus, Flatten[#1]]], ca] (* Count ON cells at each stage *)
Part[on, 2^Range[0, Log[2, stages]]] (* Extract relevant terms *)
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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