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A283197
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Number of n X 2 0..1 arrays with no 1 equal to more than two of its horizontal and vertical neighbors, with the exception of exactly one element.
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2
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0, 0, 6, 36, 176, 824, 3668, 15808, 66640, 276184, 1129482, 4570084, 18329920, 72981648, 288779688, 1136580576, 4452663936, 17372989712, 67541322638, 261743811012, 1011439313456, 3898369209992, 14990343112316, 57519762677984
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OFFSET
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1,3
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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) - 5*a(n-2) - 8*a(n-3) - 18*a(n-4) - 4*a(n-5) + 6*a(n-6) + 8*a(n-7) + 3*a(n-8) - 2*a(n-9) - a(n-10).
Empirical g.f.: 2*x^3*(1 + x)*(3 - 3*x - 2*x^2) / (1 - 3*x - 2*x^2 - 2*x^3 + x^4 + x^5)^2. - Colin Barker, Mar 22 2018
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EXAMPLE
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Some solutions for n=4:
..1..0. .1..1. .0..0. .0..1. .1..0. .0..1. .0..1. .0..0. .0..0. .1..1
..0..1. .1..0. .0..1. .1..1. .1..1. .1..1. .1..0. .1..1. .1..1. .1..1
..1..1. .1..1. .1..1. .0..1. .1..0. .0..1. .1..1. .1..1. .1..1. .1..0
..0..1. .1..0. .1..1. .1..1. .1..1. .0..0. .1..0. .1..0. .0..1. .0..0
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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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