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A271300 First differences of number of active (ON,black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 347", based on the 5-celled von Neumann neighborhood. 1
4, 0, 39, -39, 104, -93, 197, -200, 323, -299, 455, -459, 639, -603, 832, -841, 1077, -1052, 1347, -1339, 1644, -1617, 1937, -1921, 2329, -2328, 2663, -2583, 3028, -3025, 3509, -3533, 4037, -3949, 4441, -4473, 5073, -5017, 5593, -5560, 6043, -5931, 6587 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
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=347; 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}];
on=Map[Function[Apply[Plus, Flatten[#1]]], ca] (* Count ON cells at each stage *)
Table[on[[i+1]]-on[[i]], {i, 1, Length[on]-1}] (* Difference at each stage *)
CROSSREFS
Cf. A271297.
Sequence in context: A270159 A270213 A270184 * A271120 A174083 A123936
KEYWORD
sign,easy
AUTHOR
Robert Price, Apr 03 2016
STATUS
approved

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Last modified December 11 05:29 EST 2023. Contains 367717 sequences. (Running on oeis4.)