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A252401
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Number of (n+2) X (2+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 2 3 4 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 2 3 4 6 or 7.
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1
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661, 442, 688, 1224, 2414, 5061, 10129, 21427, 46070, 93671, 200430, 433693, 885001, 1898578, 4117127, 8413072, 18067521, 39215676, 80182777, 172284095, 374104916, 765132570, 1644394003, 3571453244, 7305450882, 15702421450, 34107480805
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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) = 16*a(n-3) -74*a(n-6) +141*a(n-9) -235*a(n-12) +206*a(n-15) -72*a(n-18) +16*a(n-21) +4*a(n-24) -a(n-27) for n>31.
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EXAMPLE
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Some solutions for n=4
..2..3..2..2....0..2..2..3....3..2..2..0....0..2..0..0....1..0..2..0
..3..0..1..3....3..1..3..0....2..3..2..2....3..3..0..3....0..3..3..1
..3..2..2..3....2..2..3..2....0..3..1..3....2..0..0..2....0..2..0..0
..2..3..2..2....0..2..2..3....3..2..2..3....0..2..0..0....0..0..2..0
..3..3..1..0....3..1..3..0....2..3..2..2....3..3..0..3....0..3..3..0
..3..2..2..3....2..2..3..2....3..0..1..3....2..0..1..2....0..2..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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