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A218837
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Unmatched value maps: number of n X 3 binary arrays indicating the locations of corresponding elements not equal to any horizontal or antidiagonal neighbor in a random 0..1 n X 3 array.
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2
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4, 20, 93, 436, 2043, 9573, 44857, 210190, 984904, 4615043, 21625074, 101330329, 474811581, 2224862385, 10425214612, 48850257184, 228901534957, 1072582125992, 5025883366023, 23550181377025, 110350957732161, 517080258425742
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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) + 3*a(n-2) + a(n-3).
Empirical g.f.: x*(2 + x)^2 / (1 - 4*x - 3*x^2 - x^3). - Colin Barker, Mar 10 2018
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EXAMPLE
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Some solutions for n=3:
..1..1..0....1..0..0....1..0..0....1..1..0....1..0..0....0..0..0....0..0..0
..0..0..0....1..0..0....0..0..1....0..0..1....1..0..1....1..0..0....0..0..0
..0..1..1....1..0..1....0..0..0....0..0..1....1..1..1....1..0..1....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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