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A271259
Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 326", based on the 5-celled von Neumann neighborhood.
4
1, 5, 4, 20, 9, 37, 24, 64, 13, 57, 44, 140, 49, 165, 68, 188, 72, 256, 136, 376, 125, 449, 216, 576, 197, 569, 288, 728, 273, 741, 300, 908, 413, 1033, 348, 1092, 505, 1269, 436, 1148, 537, 1461, 636, 1660, 608, 1720, 792, 2072, 760, 2152, 944, 2432, 988
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=326; 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: A271598 A271133 A272085 * A271409 A246326 A272506
KEYWORD
nonn,easy
AUTHOR
Robert Price, Apr 02 2016
STATUS
approved