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A228502
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Number of n X 4 binary arrays with top left value 1 and no two ones adjacent horizontally, vertically, diagonally or antidiagonally.
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1
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3, 5, 29, 87, 358, 1252, 4749, 17285, 64235, 236211, 873250, 3219652, 11886927, 43856285, 161862005, 597285195, 2204231074, 8134165648, 30017792409, 110774426621, 408792375587, 1508567655759, 5567079710158, 20544224979592
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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) = 2*a(n-1) + 7*a(n-2) - 2*a(n-3) - 3*a(n-4).
Empirical g.f.: x*(1 - x)*(3 + 2*x) / (1 - 2*x - 7*x^2 + 2*x^3 + 3*x^4). - Colin Barker, Sep 12 2018
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EXAMPLE
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Some solutions for n=4:
..1..0..1..0....1..0..1..0....1..0..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..0....0..0..0..0
..0..0..1..0....0..0..0..0....0..0..0..0....0..0..1..0....0..0..0..0
..1..0..0..0....0..0..0..1....1..0..0..1....1..0..0..0....1..0..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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