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A238649
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Number of (n+2) X (3+2) 0..1 arrays with no element equal to all horizontal neighbors or equal to all vertical neighbors, and new values 0..1 introduced in row major order.
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1
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3, 18, 51, 189, 630, 2187, 7473, 25692, 88119, 302511, 1038144, 3563151, 12228903, 41971050, 144048471, 494389041, 1696791534, 5823557223, 19987023645, 68597444364, 235433215419, 808030095435, 2773239244320, 9518031521451
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-1) + 5*a(n-2) - a(n-4).
Empirical g.f.: 3*x*(1 + 4*x - x^3) / (1 - 2*x - 5*x^2 + x^4). - Colin Barker, Oct 24 2018
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EXAMPLE
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Some solutions for n=5:
..0..1..1..0..1....0..1..0..1..0....0..1..0..1..0....0..1..0..0..1
..1..0..0..1..0....1..0..1..0..1....1..0..1..0..1....1..0..1..1..0
..1..0..1..0..1....0..1..0..0..1....0..1..0..1..0....0..1..0..1..0
..0..1..1..0..1....0..1..0..1..0....1..0..1..0..1....0..1..1..0..1
..1..0..0..1..0....1..0..1..0..1....0..1..0..1..0....1..0..1..1..0
..0..1..0..0..1....1..0..0..1..0....1..0..0..1..0....1..0..0..1..0
..1..0..1..1..0....0..1..1..0..1....0..1..1..0..1....0..1..1..0..1
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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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