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A188501
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Number of n X 2 binary arrays without the pattern 0 1 0 diagonally, vertically or horizontally.
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10
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4, 16, 49, 144, 441, 1369, 4225, 12996, 40000, 123201, 379456, 1168561, 3598609, 11082241, 34128964, 105103504, 323676081, 996791184, 3069714025, 9453478441, 29112890625, 89655929476, 276104007936, 850288696321, 2618545348864
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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)=3*a(n-1)-a(n-2)+3*a(n-3)+3*a(n-4)-a(n-5)-a(n-6).
Empirical g.f.: x*(4 + 4*x + 5*x^2 + x^3 - 2*x^4 - x^5) / ((1 - x + 2*x^2 - x^3)*(1 - 2*x - 3*x^2 - x^3)). - Colin Barker, Feb 18 2018
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EXAMPLE
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Some solutions for 3 X 2:
..1..1....0..1....1..1....1..1....0..1....1..0....0..1....1..1....1..1....0..1
..1..0....1..0....1..1....0..0....0..1....1..0....0..0....0..1....0..1....0..0
..1..0....1..0....1..0....1..0....1..1....0..1....1..1....1..1....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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