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A185858
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1/128 the number of (n+2) X 3 binary arrays with no 3 X 3 subblock trace equal to any horizontal or vertical neighbor 3 X 3 subblock trace.
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1
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4, 22, 124, 694, 3892, 21814, 122284, 685462, 3842404, 21538774, 120736732, 676795894, 3793814164, 21266419702, 119210006284, 668237802454, 3745841266372, 20997505287574, 117702592547644, 659787917778742
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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) = 4*a(n-1) + 9*a(n-2).
G.f.: 2*x*(2 + 3*x) / (1 - 4*x - 9*x^2).
a(n) = ((2 - sqrt(13))^n*(-4+sqrt(13)) + (2+sqrt(13))^n*(4+sqrt(13))) / (3*sqrt(13)).
(End)
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EXAMPLE
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Some solutions for 4 X 3:
..0..0..0....1..0..0....0..1..1....0..0..0....0..0..1....0..1..0....1..0..0
..0..1..1....0..1..0....0..1..1....1..0..1....1..0..1....1..1..0....1..1..0
..0..0..1....0..0..1....0..1..0....0..0..0....0..1..1....0..1..0....0..0..1
..0..1..0....0..1..0....0..1..1....1..0..0....1..1..0....1..0..0....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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