

A271408


First differences of number of active (ON,black) cells in nth stage of growth of twodimensional cellular automaton defined by "Rule 355", based on the 5celled von Neumann neighborhood.


1



4, 4, 23, 15, 84, 65, 137, 136, 252, 225, 369, 352, 551, 483, 608, 633, 937, 892, 1080, 1032, 1368, 1329, 1573, 1604, 1903, 1811, 2232, 2177, 2581, 2524, 2863, 2863, 3287, 3123, 3640, 3661, 4165, 4100, 4631, 4627, 5091, 5003, 5592, 5561
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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

Robert Price, Table of n, a(n) for n = 0..127
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 5Neighbor 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=355; 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+1n, k1+n]], {j, k+1n, k1+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. A271397.
Sequence in context: A271538 A271457 A268194 * A271249 A271167 A271155
Adjacent sequences: A271405 A271406 A271407 * A271409 A271410 A271411


KEYWORD

sign,easy


AUTHOR

Robert Price, Apr 06 2016


STATUS

approved



