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A287129 Binary representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 245", based on the 5-celled von Neumann neighborhood. 5
1, 10, 0, 1110, 11, 111110, 11, 11111100, 11, 1111111100, 11, 111111111100, 11, 11111111111100, 11, 1111111111111100, 11, 111111111111111100, 11, 11111111111111111100, 11, 1111111111111111111100, 11, 111111111111111111111100, 11, 11111111111111111111111100 (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..126

Robert Price, Diagrams of 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

Wolfram Research, Wolfram Atlas of Simple Programs

Index entries for sequences related to cellular automata

Index to 2D 5-Neighbor Cellular Automata

Index to Elementary Cellular Automata

FORMULA

Conjectures from Colin Barker, May 20 2017: (Start)

G.f.: (1 + 10*x - 101*x^2 + 100*x^3 + 111*x^4 - 1100*x^6 - 10*x^7 + 1000*x^9) / ((1 - x)*(1 + x)*(1 - 10*x)*(1 + 10*x)).

a(n) = 11 for n>5 and even.

a(n) = 10*(10^n - 10)/9 for n>5 and odd.

(End)

MATHEMATICA

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

code = 245; 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}];

Table[FromDigits[Part[ca[[i]] [[i]], Range[i, 2 * i - 1]], 10], {i, 1, stages - 1}]

CROSSREFS

Cf. A287130, A287131, A287132.

Sequence in context: A286770 A286503 A286403 * A287190 A277926 A222521

Adjacent sequences:  A287126 A287127 A287128 * A287130 A287131 A287132

KEYWORD

nonn,easy

AUTHOR

Robert Price, May 20 2017

STATUS

approved

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Last modified December 2 11:44 EST 2021. Contains 349440 sequences. (Running on oeis4.)