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A273538
Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 779", based on the 5-celled von Neumann neighborhood.
4
1, 5, 17, 37, 61, 97, 125, 197, 237, 305, 337, 473, 521, 617, 629, 901, 973, 1105, 1137, 1401, 1449, 1609, 1561, 2089, 2169, 2361, 2345, 2785, 2785, 3001, 2789, 3845, 3981, 4241, 4273, 4793, 4841, 5129, 4953, 5993, 6073, 6393, 6249, 7073, 6945, 7289, 6697
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=779; 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: A264904 A257582 A339988 * A273212 A273274 A357058
KEYWORD
nonn,easy
AUTHOR
Robert Price, May 24 2016
STATUS
approved