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A209822
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Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having one or two distinct values, and new values 0..2 introduced in row major order.
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1
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8, 41, 218, 1169, 6278, 33725, 181178, 973337, 5229038, 28091861, 150917378, 810770609, 4355687798, 23399980205, 125711276618, 675356343497, 3628204270718, 19491734040581, 104715078744338, 562558861802849
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 2*a(n-3).
Empirical g.f.: x*(8 - 7*x - 4*x^2) / ((1 - x)*(1 - 5*x - 2*x^2)). - Colin Barker, Jul 13 2018
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EXAMPLE
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Some solutions for n=4:
..0..0....0..1....0..1....0..0....0..0....0..0....0..0....0..0....0..0....0..1
..1..1....0..0....0..0....0..0....0..1....0..1....1..1....0..1....0..0....1..0
..1..1....2..2....2..0....1..0....1..0....0..1....1..0....0..0....0..1....1..0
..0..0....2..0....0..0....0..1....0..0....1..0....0..0....0..1....0..0....0..0
..1..0....2..2....2..2....0..0....1..0....1..1....2..2....1..0....1..0....2..2
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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