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A267780 Decimal representation of the n-th iteration of the "Rule 211" elementary cellular automaton starting with a single ON (black) cell. 1
1, 5, 25, 125, 505, 2045, 8185, 32765, 131065, 524285, 2097145, 8388605, 33554425, 134217725, 536870905, 2147483645, 8589934585, 34359738365, 137438953465, 549755813885, 2199023255545, 8796093022205, 35184372088825, 140737488355325, 562949953421305 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.

LINKS

Robert Price, Table of n, a(n) for n = 0..1000

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 Elementary Cellular Automata

FORMULA

Conjectures from Colin Barker, Jan 20 2016 and Apr 20 2019: (Start)

a(n) = 4*a(n-1)+a(n-2)-4*a(n-3) for n>3.

G.f.: (1+x+4*x^2+24*x^3) / ((1-x)*(1+x)*(1-4*x)).

(End)

MATHEMATICA

rule=211; 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 *)

CROSSREFS

Cf. A267778.

Sequence in context: A061974 A015950 A337950 * A228736 A126642 A269615

Adjacent sequences:  A267777 A267778 A267779 * A267781 A267782 A267783

KEYWORD

nonn,easy

AUTHOR

Robert Price, Jan 20 2016

STATUS

approved

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Last modified November 26 01:22 EST 2020. Contains 338631 sequences. (Running on oeis4.)