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A223189
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Number of nX2 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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1
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9, 81, 256, 2500, 19044, 149769, 1306449, 11573604, 98962704, 945378009, 8103240324, 71267107681, 649113816976, 5922783740329, 51729783444964, 469159715409025, 4214751562369924, 37759790203876225, 340491211679997504
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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
..0..2....2..2....2..2....0..2....2..2....2..2....0..2....2..1....0..1....1..0
..0..1....1..1....2..0....0..0....0..0....2..1....0..1....0..0....0..0....1..0
..0..2....1..0....2..0....2..0....1..1....2..0....1..2....1..2....1..1....2..1
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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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