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A283134 Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 581", based on the 5-celled von Neumann neighborhood. 4
1, 2, 4, 11, 17, 46, 64, 183, 259, 757, 1056, 2911, 4111, 12151, 16899, 46573, 65728, 194367, 271071, 742415, 1049591, 3110371, 4333661, 11918728, 16812119, 49772419, 69346117, 190141496, 268436181, 795964416, 1110320017, 3049608558, 4305977348, 12734264283 (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
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
MATHEMATICA
CAStep[rule_, a_] := Map[rule[[10 - #]] &, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}];
code = 581; 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[1, i]], 2], {i, 1, stages - 1}]
CROSSREFS
Sequence in context: A018625 A360401 A123557 * A283216 A283293 A283389
KEYWORD
nonn,easy
AUTHOR
Robert Price, Mar 01 2017
STATUS
approved

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Last modified April 23 10:13 EDT 2024. Contains 371905 sequences. (Running on oeis4.)