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A272789
First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 534", based on the 5-celled von Neumann neighborhood.
1
4, 4, 12, -4, 32, -20, 48, -32, 92, -76, 80, -48, 156, -108, 136, -116, 240, -216, 232, -184, 340, -284, 324, -308, 492, -464, 440, -388, 736, -688, 636, -488, 868, -976, 700, -340, 872, -900, 844, -748, 1068, -1104, 1024, -948, 1536, -1412, 1324, -1080
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.
MATHEMATICA
CAStep[rule_, a_]:=Map[rule[[10-#]]&, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}];
code=534; 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. A272786.
Sequence in context: A109045 A079315 A229253 * A273152 A322785 A189545
KEYWORD
sign,easy
AUTHOR
Robert Price, May 06 2016
STATUS
approved