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A271095
Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 278", based on the 5-celled von Neumann neighborhood.
4
1, 5, 8, 20, 16, 44, 32, 88, 44, 132, 60, 196, 89, 257, 100, 332, 165, 425, 160, 512, 249, 637, 232, 720, 345, 925, 332, 996, 465, 1233, 428, 1276, 560, 1512, 556, 1656, 656, 1864, 697, 2053, 804, 2288, 824, 2452, 981, 2773, 1008, 3028, 1024, 3044, 1284
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=278; 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: A197539 A034453 A269715 * A194266 A169703 A270091
KEYWORD
nonn,easy
AUTHOR
Robert Price, Mar 30 2016
STATUS
approved