A271156 Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 302", based on the 5-celled von Neumann neighborhood.

1, 5, 8, 21, 24, 37, 44, 85, 96, 85, 100, 165, 120, 180, 205, 320, 372, 257, 308, 436, 276, 348, 392, 524, 528, 500, 552, 688, 576, 760, 848, 1168, 1352, 932, 1064, 1436, 760, 1136, 1208, 1280, 1220, 1236, 1244, 1412, 1360, 1404, 1480, 1892, 1928, 1696, 1720

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=302; 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: A271281 A246330 A034737 * A272115 A268195 A169705

Adjacent sequences: A271153 A271154 A271155 * A271157 A271158 A271159

Keyword

nonn,easy,changed

Author

Robert Price, Mar 31 2016

Status

approved