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A283858
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Number of 2 X n 0..1 arrays with no 1 equal to more than three of its horizontal, diagonal and antidiagonal neighbors.
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1
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4, 16, 61, 233, 896, 3444, 13225, 50789, 195076, 749256, 2877717, 11052673, 42450984, 163045180, 626221537, 2405182717, 9237791852, 35480380112, 136272540429, 523393640665, 2010242874320, 7720912327300, 29654370583449
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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) = 3*a(n-1) + a(n-2) + 7*a(n-3) + 6*a(n-4).
Empirical g.f.: x*(4 + 4*x + 9*x^2 + 6*x^3) / (1 - 3*x - x^2 - 7*x^3 - 6*x^4). - Colin Barker, Feb 22 2019
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EXAMPLE
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Some solutions for n=4:
..0..0..1..0. .1..0..0..0. .0..0..0..1. .0..1..1..0. .1..1..1..0
..1..0..0..1. .1..1..1..1. .1..0..0..1. .0..1..0..1. .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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