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A209890 Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having two distinct values, and new values 0..2 introduced in row major order. 1
7, 34, 164, 792, 3824, 18464, 89152, 430464, 2078464, 10035712, 48456704, 233969664, 1129705472, 5454700544, 26337624064, 127169298432, 614027689984, 2964787953664, 14315262574592, 69120202113024, 333741858750464 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A209897.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 4*a(n-1) +4*a(n-2).

Empirical G.f.: x*(7+6*x)/(1-4*x-4*x^2). [Colin Barker, Mar 15 2012]

EXAMPLE

Some solutions for n=4:

..0..1....0..1....0..0....0..0....0..0....0..0....0..0....0..1....0..0....0..1

..1..0....0..0....0..1....0..1....0..1....1..1....1..0....1..0....0..1....0..0

..1..0....2..0....0..0....0..1....1..0....1..0....1..0....1..0....1..0....2..2

..0..0....0..0....2..0....1..0....0..1....0..0....0..0....1..0....0..0....2..0

..2..2....2..2....0..0....1..1....0..0....2..2....0..2....0..1....1..0....2..2

CROSSREFS

Sequence in context: A032206 A124466 A055271 * A027209 A209807 A080048

Adjacent sequences:  A209887 A209888 A209889 * A209891 A209892 A209893

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 14 2012

STATUS

approved

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Last modified July 20 01:17 EDT 2019. Contains 325168 sequences. (Running on oeis4.)