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A270675
Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 187", based on the 5-celled von Neumann neighborhood.
1
1, 6, 15, 56, 77, 170, 219, 404, 465, 766, 863, 1304, 1445, 2026, 2247, 3008, 3245, 4250, 4523, 5796, 6113, 7654, 8063, 9880, 10357, 12506, 13075, 15548, 16265, 19022, 19959, 23048, 24021, 27586, 28595, 32684, 33737, 38350, 39495, 44640, 45853, 51586, 52891
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=187; 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}];
on=Map[Function[Apply[Plus, Flatten[#1]]], ca] (* Count ON cells at each stage *)
Table[Total[Part[on, Range[1, i]]], {i, 1, Length[on]}] (* Sum at each stage *)
CROSSREFS
Cf. A270673.
Sequence in context: A093042 A373569 A270624 * A271002 A271018 A145638
KEYWORD
nonn,easy
AUTHOR
Robert Price, Mar 21 2016
STATUS
approved