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A213690
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Half the number of (n+1)X(n+1) symmetric 0..1 arrays with no 2X2 subblock summing to 2
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1
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3, 13, 70, 529, 5148, 68798, 1220409, 29377751, 949700962, 41536397680, 2450653487731, 195553849371916, 21091722699002539, 3077853629320011499, 607688763160596614184, 162407853243770174812161
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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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EXAMPLE
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Some solutions for n=4
..1..0..0..0..0....0..0..1..0..1....0..1..0..1..0....1..1..0..1..1
..0..0..1..0..1....0..1..1..1..1....1..1..1..1..1....1..1..1..1..1
..0..1..1..1..1....1..1..0..1..0....0..1..1..1..1....0..1..1..1..0
..0..0..1..1..1....0..1..1..1..1....1..1..1..0..1....1..1..1..0..0
..0..1..1..1..1....1..1..0..1..0....0..1..1..1..1....1..1..0..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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