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A273577
Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 803", based on the 5-celled von Neumann neighborhood.
3
1, 5, 21, 33, 77, 105, 153, 161, 285, 345, 425, 465, 609, 665, 777, 705, 1085, 1209, 1353, 1457, 1665, 1785, 1961, 1953, 2385, 2537, 2745, 2769, 3185, 3225, 3465, 2945, 4221, 4473, 4745, 4977, 5313, 5561, 5865, 5985, 6545, 6825, 7161, 7313, 7857, 8025, 8393
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=803; 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: A317425 A074074 A006309 * A317039 A317693 A145026
KEYWORD
nonn,easy
AUTHOR
Robert Price, May 25 2016
STATUS
approved