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A272293
Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 461", based on the 5-celled von Neumann neighborhood.
1
1, 9, 14, 58, 75, 187, 208, 412, 437, 765, 810, 1290, 1371, 2031, 2136, 3016, 3117, 4241, 4406, 5786, 5983, 7647, 7864, 9864, 10129, 12485, 12822, 15578, 15983, 19139, 19616, 23196, 23717, 27745, 28370, 32942, 33563, 38703, 39472, 45128, 45977, 52129, 52954
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.
MATHEMATICA
CAStep[rule_, a_]:=Map[rule[[10-#]]&, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}];
code=461; 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[Total[Part[on, Range[1, i]]], {i, 1, Length[on]}] (* Sum at each stage *)
CROSSREFS
Cf. A272291.
Sequence in context: A272566 A271691 A272113 * A272545 A272009 A298754
KEYWORD
nonn,easy
AUTHOR
Robert Price, Apr 24 2016
STATUS
approved