A281283 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 350", based on the 5-celled von Neumann neighborhood.

1, 3, 6, 13, 27, 52, 110, 211, 444, 834, 1773, 3391, 7104, 13346, 28373, 54063, 114136, 213542, 453977, 864935, 1826264, 3416614, 7264089, 13838503, 29220312, 54665766, 116225881, 221415591, 467525080, 874652198, 1859614553, 3542648999, 7480401368

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 Chai Wah Wu, May 05 2024: (Start)

a(n) = 17*a(n-4) - 16*a(n-8) for n > 23.

G.f.: (-384*x^23 + 448*x^22 - 64*x^21 - 384*x^20 + 120*x^19 + 4*x^18 + 4*x^17 + 472*x^16 - 208*x^15 - 8*x^14 - 12*x^12 + 12*x^11 - x^10 - 2*x^9 + x^8 - 10*x^7 + 8*x^6 + x^5 + 10*x^4 + 13*x^3 + 6*x^2 + 3*x + 1)/(16*x^8 - 17*x^4 + 1). (End)

Mathematica

CAStep[rule_, a_] := Map[rule[[10 - #]] &, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}];
code = 350; 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

Cf. A281281, A281282, A281284.

Sequence in context: A273226 A291726 A280563 * A281638 A281100 A276129

Adjacent sequences: A281280 A281281 A281282 * A281284 A281285 A281286

Keyword

nonn,easy

Author

Robert Price, Jan 18 2017

Status

approved