login
A273760
Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 902", based on the 5-celled von Neumann neighborhood.
1
1, 6, 11, 28, 37, 66, 83, 144, 165, 230, 283, 388, 453, 590, 671, 904, 1013, 1230, 1359, 1696, 1869, 2182, 2439, 2868, 3185, 3682, 4023, 4668, 5061, 5762, 6231, 7008, 7705, 8438, 9143, 10148, 10837, 11682, 12523, 13688, 14617, 15850, 16959, 18172, 19273
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=902; 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. A273758.
Sequence in context: A087737 A273328 A273423 * A273837 A273409 A273484
KEYWORD
nonn,easy
AUTHOR
Robert Price, May 29 2016
STATUS
approved