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A270156 Number of active (ON,black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 99", based on the 5-celled von Neumann neighborhood. 4
1, 5, 5, 41, 12, 109, 16, 197, 24, 325, 53, 497, 40, 661, 56, 869, 92, 1129, 108, 1369, 124, 1693, 197, 2017, 189, 2365, 189, 2729, 277, 3173, 285, 3633, 285, 4049, 333, 4613, 417, 5169, 417, 5633, 565, 6313, 477, 6849, 553, 7477, 713, 8201, 793, 8913, 701 (list; graph; refs; listen; history; text; internal format)
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.

LINKS

Robert Price, Table of n, a(n) for n = 0..128

Robert Price, Diagrams of the first 20 stages.

N. J. A. Sloane, On the Number of ON Cells in Cellular Automata, arXiv:1503.01168 [math.CO], 2015

Eric Weisstein's World of Mathematics, Elementary Cellular Automaton

S. Wolfram, A New Kind of Science

Index entries for sequences related to cellular automata

Index to 2D 5-Neighbor Cellular Automata

Index to Elementary Cellular Automata

MATHEMATICA

CAStep[rule_, a_]:=Map[rule[[10-#]]&, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}];

code=99; 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: A271277 A269829 A270058 * A270164 A270181 A270210

Adjacent sequences:  A270153 A270154 A270155 * A270157 A270158 A270159

KEYWORD

nonn,easy

AUTHOR

Robert Price, Mar 12 2016

STATUS

approved

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Last modified August 4 07:32 EDT 2020. Contains 336201 sequences. (Running on oeis4.)