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A220806
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Equals one maps: number of n X 2 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..2 n X 2 array.
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2
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2, 8, 38, 168, 726, 3088, 12974, 54000, 223118, 916552, 3747670, 15266264, 61997350, 251143328, 1015242974, 4097067104, 16510377630, 66454603032, 267215894086, 1073591223944, 4310358413046, 17295539333552, 69365195543182
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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) = 7*a(n-1) - 11*a(n-2) - 3*a(n-3) - 4*a(n-4).
Empirical g.f.: 2*x*(1 - 3*x + 2*x^2 - 2*x^3) / ((1 - 4*x)*(1 - 3*x - x^2 - x^3)). - Colin Barker, Mar 13 2018
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EXAMPLE
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Some solutions for n=3:
..0..0....0..0....1..1....0..0....1..0....0..1....0..0....0..1....0..0....1..0
..0..0....0..1....1..0....1..0....1..0....1..0....0..0....0..0....0..0....0..0
..1..0....1..0....0..1....1..0....0..0....1..1....0..0....1..0....1..1....1..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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