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A272111
Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 429", based on the 5-celled von Neumann neighborhood.
4
1, 8, 5, 44, 17, 108, 33, 208, 57, 328, 85, 500, 97, 648, 149, 920, 161, 1100, 257, 1468, 177, 1708, 289, 2120, 321, 2360, 501, 2908, 385, 3200, 589, 3764, 617, 4076, 785, 4812, 693, 5188, 993, 5924, 957, 6340, 1245, 7200, 1145, 7544, 1465, 8652, 1141, 9152
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.
MATHEMATICA
CAStep[rule_, a_]:=Map[rule[[10-#]]&, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}];
code=429; 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: A272153 A272564 A271689 * A272291 A272543 A272007
KEYWORD
nonn,easy
AUTHOR
Robert Price, Apr 20 2016
STATUS
approved