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A270736 First differences of number of active (ON,black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 206", based on the 5-celled von Neumann neighborhood. 1
4, 3, 12, 0, 12, 16, 16, 8, 20, 0, 24, 32, 8, 56, 48, 12, 24, -24, 24, 44, 56, 20, 20, 68, 20, 56, 88, 36, 96, 172, 120, -12, -48, 72, 56, 16, 64, 40, 8, 164, 120, 52, 0, 56, 176, 160, 124, 84, 116, 36, 128, 36, 100, 36, 88, 244, 148, 100, 140, 108, 156, 436 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

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..127

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=206; 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[on[[i+1]]-on[[i]], {i, 1, Length[on]-1}] (* Difference at each stage *)

CROSSREFS

Cf. A270733.

Sequence in context: A191617 A169704 A270094 * A270171 A270987 A204291

Adjacent sequences:  A270733 A270734 A270735 * A270737 A270738 A270739

KEYWORD

sign,easy

AUTHOR

Robert Price, Mar 22 2016

STATUS

approved

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Last modified October 6 16:34 EDT 2022. Contains 357270 sequences. (Running on oeis4.)