A270232 Number of active (ON,black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 133", based on the 5-celled von Neumann neighborhood.

1, 8, 4, 40, 17, 100, 25, 184, 56, 317, 48, 429, 120, 649, 72, 833, 128, 1073, 168, 1233, 312, 1629, 112, 2045, 280, 2160, 405, 2552, 393, 3084, 377, 3396, 529, 3872, 537, 4192, 781, 4872, 625, 5424, 717, 5904, 861, 6436, 913, 7248, 921, 7668, 1241, 8412

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=133; 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: A082682 A279635 A213505 * A270716 A270457 A270946

Adjacent sequences: A270229 A270230 A270231 * A270233 A270234 A270235

Keyword

nonn,easy

Author

Robert Price, Mar 13 2016

Status

approved