OFFSET
0,2
COMMENTS
Initialized with a single black (ON) cell at stage zero.
Rules 38, 70, 102, 134, 166, 198 and 230 also generate this sequence.
Apparently a duplicate of A003947. - R. J. Mathar, Mar 09 2016
REFERENCES
S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 170.
LINKS
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
FORMULA
Conjectures from Colin Barker, Mar 08 2016: (Start)
a(n) = 5*4^(n-1) for n>0.
a(n) = 4*a(n-1) for n>1.
G.f.: (1+x) / (1-4*x).
(End)
MATHEMATICA
rule=6; stages=300;
ca=CellularAutomaton[{rule, {2, {{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}}, {1, 1}}, {{{1}}, 0}, stages]; (* Start with single black cell *)
on=Map[Function[Apply[Plus, Flatten[#1]]], ca] (* Count ON cells at each stage *)
Part[on, 2^Range[0, Log[2, stages]]] (* Extract relevant terms *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Robert Price, Mar 03 2016
EXTENSIONS
a(9)-a(15) from Lars Blomberg, Apr 12 2016
STATUS
approved