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A223187
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Number of n X n 0..2 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.
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0
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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=3
..2..2..2....0..0..0....1..0..1....1..0..0....2..0..2....2..1..1....2..0..2
..1..0..0....1..0..0....1..0..1....1..0..1....2..0..1....2..0..1....1..0..1
..0..0..0....2..0..1....1..0..2....2..2..2....2..2..2....2..0..1....2..0..1
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CROSSREFS
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KEYWORD
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nonn,changed
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AUTHOR
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STATUS
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approved
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