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A266180
Decimal representation of the n-th iteration of the "Rule 6" elementary cellular automaton starting with a single ON (black) cell.
6
1, 6, 16, 96, 256, 1536, 4096, 24576, 65536, 393216, 1048576, 6291456, 16777216, 100663296, 268435456, 1610612736, 4294967296, 25769803776, 68719476736, 412316860416, 1099511627776, 6597069766656, 17592186044416, 105553116266496, 281474976710656
OFFSET
0,2
COMMENTS
A001025 is a subsequence. - Altug Alkan, Dec 23 2015
Rules 38, 134 and 166 also generate this sequence.
REFERENCES
S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.
FORMULA
From Colin Barker, Dec 23 2015 and Apr 13 2019: (Start)
a(n) = 4^(n-1)*(5-(-1)^n).
a(n) = 16*a(n-2) for n>1.
G.f.: (1+6*x) / ((1-4*x)*(1+4*x)).
(End)
MATHEMATICA
rule=6; rows=20; ca=CellularAutomaton[rule, {{1}, 0}, rows-1, {All, All}]; (* Start with single black cell *) catri=Table[Take[ca[[k]], {rows-k+1, rows+k-1}], {k, 1, rows}]; (* Truncated list of each row *) Table[FromDigits[catri[[k]], 2], {k, 1, rows}] (* Decimal Representation of Rows *)
LinearRecurrence[{0, 16}, {1, 6}, 30] (* Harvey P. Dale, May 25 2016 *)
PROG
(Python) print([int(4**(n-1)*(5-(-1)**n)) for n in range(30)]) # Karl V. Keller, Jr., Jun 03 2021
KEYWORD
nonn,easy
AUTHOR
Robert Price, Dec 22 2015
STATUS
approved