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A209841
Number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having one or two distinct values, and new values 0..3 introduced in row major order.
1
8, 41, 227, 1331, 8123, 50987, 326123, 2111531, 13777067, 90322091, 593895083, 3912075947, 25797704363, 170233203371, 1123784731307, 7420419975851, 49004773878443, 323658783566507, 2137765638482603, 14120404331440811
OFFSET
1,1
COMMENTS
Column 1 of A209848.
LINKS
FORMULA
Empirical: a(n) = 11*a(n-1) - 30*a(n-2) + 4*a(n-3) + 16*a(n-4).
Empirical g.f.: x*(8 - 47*x + 16*x^2 + 32*x^3) / ((1 - x)*(1 - 4*x)*(1 - 6*x - 4*x^2)). - Colin Barker, Jul 13 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..1....0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..1
..0..0....0..0....0..1....1..0....0..0....0..0....1..0....0..0....0..0....0..0
..1..0....0..1....0..0....0..1....0..0....0..0....0..1....0..0....0..1....2..2
..0..0....0..1....0..0....1..0....1..0....0..0....1..0....1..0....0..0....0..0
..2..0....0..0....0..0....0..1....1..0....0..0....0..0....0..0....2..2....2..2
CROSSREFS
Cf. A209848.
Sequence in context: A265149 A209822 A051737 * A196927 A188209 A026953
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 14 2012
STATUS
approved