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A208029
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Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 1 0 1 vertically.
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1
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9, 81, 279, 1377, 5895, 26685, 118179, 527913, 2350215, 10476981, 46680363, 208028817, 926993439, 4130894781, 18407971395, 82029484089, 365538508695, 1628908337349, 7258719524571, 32346212936481, 144140772230991
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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) + 11*a(n-2) + 2*a(n-3) - 10*a(n-4).
Empirical g.f.: 9*x*(1 - x)*(1 + 8*x + 10*x^2) / (1 - 2*x - 11*x^2 - 2*x^3 + 10*x^4). - Colin Barker, Jun 26 2018
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EXAMPLE
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Some solutions for n=4:
..1..1..0..0....0..1..0..1....1..0..1..1....1..0..1..1....0..1..1..0
..0..1..1..1....0..1..1..0....1..0..1..0....1..0..1..0....1..1..0..0
..0..1..1..0....1..1..0..0....1..1..0..0....1..1..0..0....1..1..0..1
..1..1..0..0....0..1..0..1....1..1..0..1....0..1..0..1....1..1..1..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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