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A212130
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Number of n X n binary matrices with zero diagonal and no directed 3-loops (3-loop: x(i,j)*x(j,k)*x(k,i)=1, and i,j,k all different)
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0
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OFFSET
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1,2
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LINKS
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EXAMPLE
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Some solutions for n=4
..0..1..0..1....0..0..1..0....0..1..0..1....0..0..1..0....0..0..1..1
..0..0..1..0....0..0..0..0....0..0..1..0....1..0..0..1....0..0..1..1
..0..0..0..1....1..1..0..0....0..0..0..1....0..0..0..0....0..0..0..0
..1..0..1..0....0..1..1..0....0..0..1..0....1..1..1..0....1..1..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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