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A272753 First differences of number of active (ON,black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 531", based on the 5-celled von Neumann neighborhood. 1
4, 8, 16, 20, 40, 8, 68, 12, 96, 4, 108, 4, 156, 4, 152, -4, 192, 28, 140, 40, 204, 108, 148, 124, 244, -104, 392, -40, 292, 136, 220, 32, 340, 60, 288, -60, 508, 68, 380, 56, 360, -56, 760, -176, 552, -184, 840, -216, 632, -52, 724, -288, 832, -124, 584 (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

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 5-Neighbor 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=531; 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. A272750.

Sequence in context: A312806 A036693 A181471 * A272804 A237990 A312807

Adjacent sequences:  A272750 A272751 A272752 * A272754 A272755 A272756

KEYWORD

sign,easy

AUTHOR

Robert Price, May 05 2016

STATUS

approved

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Last modified May 21 15:12 EDT 2019. Contains 323444 sequences. (Running on oeis4.)