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A219150
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Unchanging value maps: number of n X 2 binary arrays indicating the locations of corresponding elements unequal to no horizontal, antidiagonal or vertical neighbor in a random 0..1 n X 2 array.
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1
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2, 4, 9, 21, 49, 115, 269, 628, 1468, 3433, 8025, 18758, 43851, 102512, 239638, 560193, 1309554, 3061318, 7156366, 16729268, 39107635, 91421020, 213712795, 499591476, 1167883505, 2730134349, 6382172117, 14919456700, 34876870155, 81530855583
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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) - a(n-2) + 4*a(n-3) + a(n-5).
Empirical g.f.: x*(2 + 3*x^2 - x^3) / (1 - 2*x + x^2 - 4*x^3 - x^5). - Colin Barker, Jul 25 2018
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EXAMPLE
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All solutions for n=3:
..0..0....1..0....0..0....1..1....0..0....0..0....1..1....1..1....1..0
..0..0....0..0....0..0....1..1....0..0....0..1....0..0....1..0....0..0
..0..0....0..0....1..1....1..1....0..1....1..1....0..0....0..0....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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