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A208559
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Number of 7 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 0 1 1 vertically.
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1
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20, 400, 1260, 11020, 52000, 351140, 1913940, 11836400, 67894220, 407225740, 2378376000, 14112662980, 82952260180, 490344818000, 2888730695340, 17052623706380, 100542287612000, 593228737061860, 3498693917381460
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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) = a(n-1) + 31*a(n-2) + 12*a(n-3) - 144*a(n-4).
Empirical g.f.: 20*x*(1 + 19*x + 12*x^2 - 144*x^3) / (1 - x - 31*x^2 - 12*x^3 + 144*x^4). - Colin Barker, Jul 05 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..0..0....0..1..1..1....0..1..0..1....0..1..0..1....1..1..0..1
..1..1..0..1....1..0..1..0....0..1..0..0....0..1..1..0....1..0..1..1
..0..1..0..0....0..1..1..1....0..1..0..0....0..1..0..0....1..1..0..0
..0..1..0..0....1..0..1..0....0..1..0..0....0..1..1..0....1..0..1..1
..0..1..0..0....0..1..1..1....0..1..0..0....0..1..0..0....0..1..0..0
..0..1..0..0....1..0..1..0....0..1..0..0....0..1..1..0....1..0..1..1
..0..1..0..0....0..1..0..0....0..1..0..0....0..1..0..0....0..1..0..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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