

A169699


Total number of ON cells at stage n of twodimensional 5neighbor outer totalistic cellular automaton defined by "Rule 510".


17



1, 5, 12, 25, 28, 56, 56, 113, 60, 120, 120, 240, 120, 240, 240, 481, 124, 248, 248, 496, 248, 496, 496, 992, 248, 496, 496, 992, 496, 992, 992, 1985, 252, 504, 504, 1008, 504, 1008, 1008, 2016, 504, 1008, 1008, 2016, 1008, 2016, 2016, 4032, 504, 1008, 1008, 2016
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,2


COMMENTS

We work on the square grid. Each cell has 4 neighbors, N, S, E, W. If none of your 4 neighbors are ON, your state does not change. If all 4 of your neighbors are ON, your state flips. In all other cases you turn ON. We start with one ON cell.
As observed by Packard and Wolfram (see Fig. 2), a slice along the EW line shows the successive states of the 1D CA Rule 126 (see A071035, A071051).


REFERENCES

S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 170.


LINKS

Robert Price, Table of n, a(n) for n = 0..128
N. H. Packard and S. Wolfram, TwoDimensional Cellular Automata, Journal of Statistical Physics, 38 (1985), 901946.
N. J. A. Sloane, Illustration of first 28 generations
N. J. A. Sloane, On the Number of ON Cells in Cellular Automata, arXiv:1503.01168, 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


FORMULA

For n>0, it is easy to show that if 2^k <= n < 2^(k+1) then a(n) =
(2^(k+1)1)*2^(1+wt(n)), where wt is the binary weight A000120, except that if n is a power of 2 we must add 1 to the result.


EXAMPLE

When arranged into blocks of sizes 1,1,2,4,8,16,...:
1,
5,
12, 25,
28, 56, 56, 113,
60, 120, 120, 240, 120, 240, 240, 481,
124, 248, 248, 496, 248, 496, 496, 992, 248, 496, 496, 992, 496, 992, 992, 1985,
252, 504, 504, 1008, 504, 1008, 1008, 2016, 504, 1008, 1008, 2016, 1008, 2016, 2016, 4032, 504, 1008, 1008, 2016, 1008, 2016, 2016, 4032,
..., the initial terms in the rows (after the initial rows) have the form 2^m4 and the final terms are given by A092440. The row beginning with 2^m4 is divisible by 2^(m2)1 (see formula).


MAPLE

A000120 := proc(n) add(i, i=convert(n, base, 2)) end:
ht:=n>floor(log[2](n));
f:=proc(n) local a, t1;
if n=0 then 1 else
a:=(2^(ht(n)+1)1)*2^(1+A000120(n));
if 2^log[2](n)=n then a:=a+1; fi; a; fi; end;
[seq(f(n), n=0..65)]; # A169699


MATHEMATICA

Map[Function[Apply[Plus, Flatten[ #1]]], CellularAutomaton[{ 510, {2, {{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}}, {1, 1}}, {{{1}}, 0}, 100]]
ArrayPlot /@ CellularAutomaton[{510, {2, {{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}}, {1, 1}}, {{{1}}, 0}, 28]


CROSSREFS

Cf. A000120, A071035, A071051, A008574, A092440, A169700.
See A253089 for 9celled neighborhood version.
Sequence in context: A108314 A079425 A272194 * A109624 A081501 A274629
Adjacent sequences: A169696 A169697 A169698 * A169700 A169701 A169702


KEYWORD

nonn,tabf


AUTHOR

N. J. A. Sloane, Apr 17 2010


EXTENSIONS

Entry revised with more precise definition, formula and additional information, N. J. A. Sloane, Aug 24 2014


STATUS

approved



