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A273569 Number of active (ON,black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 798", based on the 5-celled von Neumann neighborhood. 4
1, 5, 13, 21, 37, 41, 85, 93, 125, 117, 209, 209, 253, 209, 421, 429, 493, 453, 641, 609, 685, 549, 985, 969, 1061, 941, 1273, 1161, 1261, 929, 1861, 1869, 1997, 1893, 2273, 2177, 2317, 1989, 2873, 2793, 2949, 2637, 3289, 2985, 3149, 2373, 4265, 4217, 4405 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Initialized with a single black (ON) cell at stage zero.
REFERENCES
S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 170.
LINKS
N. J. A. Sloane, On the Number of ON Cells in Cellular Automata, arXiv:1503.01168 [math.CO], 2015
Eric Weisstein's World of Mathematics, Elementary Cellular Automaton
MATHEMATICA
CAStep[rule_, a_]:=Map[rule[[10-#]]&, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}];
code=798; stages=128;
rule=IntegerDigits[code, 2, 10];
g=2*stages+1; (* Maximum size of grid *)
a=PadLeft[{{1}}, {g, g}, 0, Floor[{g, g}/2]]; (* Initial ON cell on grid *)
ca=a;
ca=Table[ca=CAStep[rule, ca], {n, 1, stages+1}];
PrependTo[ca, a];
(* Trim full grid to reflect growth by one cell at each stage *)
k=(Length[ca[[1]]]+1)/2;
ca=Table[Table[Part[ca[[n]][[j]], Range[k+1-n, k-1+n]], {j, k+1-n, k-1+n}], {n, 1, k}];
Map[Function[Apply[Plus, Flatten[#1]]], ca] (* Count ON cells at each stage *)
CROSSREFS
Sequence in context: A294962 A316357 A252296 * A273750 A191116 A166051
KEYWORD
nonn,easy
AUTHOR
Robert Price, May 25 2016
STATUS
approved

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Last modified March 28 08:22 EDT 2024. Contains 371236 sequences. (Running on oeis4.)