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A230984
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Number of white square subarrays of (n+1) X (3+1) binary arrays with no element equal to a strict majority of its diagonal and antidiagonal neighbors, with upper left element zero.
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2
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2, 4, 11, 24, 59, 139, 332, 796, 1903, 4563, 10934, 26209, 62835, 150636, 361156, 865882, 2076002, 4977375, 11933643, 28611925, 68599559, 164473454, 394339672, 945464381, 2266835107, 5434939417, 13030752556, 31242393432, 74906430076
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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) = 2*a(n-1) + 3*a(n-2) - 3*a(n-3) - 6*a(n-4) + 2*a(n-5) + 4*a(n-6) - a(n-7) - a(n-8).
Empirical g.f.: x*(2 - 3*x^2 - 4*x^3 + 2*x^4 + 2*x^5 - x^6) / (1 - 2*x - 3*x^2 + 3*x^3 + 6*x^4 - 2*x^5 - 4*x^6 + x^7 + x^8). - Colin Barker, Mar 18 2018
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EXAMPLE
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Some solutions for n=6:
..0..x..0..x....0..x..1..x....0..x..0..x....0..x..1..x....0..x..0..x
..x..1..x..1....x..1..x..0....x..1..x..0....x..1..x..0....x..1..x..1
..1..x..0..x....0..x..1..x....1..x..1..x....1..x..0..x....0..x..0..x
..x..0..x..0....x..1..x..0....x..0..x..0....x..0..x..1....x..1..x..1
..1..x..1..x....0..x..0..x....1..x..1..x....1..x..0..x....1..x..0..x
..x..0..x..1....x..0..x..1....x..0..x..0....x..1..x..1....x..0..x..1
..1..x..0..x....1..x..1..x....1..x..1..x....0..x..0..x....1..x..1..x
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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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