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Number of permutations of 0..floor((6*n-1)/2) on even squares of an 6*n array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing

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`%I #5 Aug 25 2012 05:56:47
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`%S 1,1,1,4,50,458,15485,234217,14296434,297246092,26970790176
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`%N Number of permutations of 0..floor((6*n-1)/2) on even squares of an 6*n array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing
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`%C Row 6 of A215788
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`%e Some solutions for n=5
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`%e ..0..x..1..x..4....0..x..1..x..2....0..x..1..x..4....0..x..1..x..2
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`%e ..x..2..x..5..x....x..3..x..4..x....x..2..x..5..x....x..3..x..4..x
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`%e ..3..x..6..x..8....5..x..6..x..7....3..x..6..x..8....5..x..6..x..8
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`%e ..x..7..x.10..x....x..8..x..9..x....x..7..x..9..x....x..7..x..9..x
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`%e ..9..x.11..x.13...10..x.11..x.13...10..x.11..x.13...10..x.11..x.12
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`%e ..x.12..x.14..x....x.12..x.14..x....x.12..x.14..x....x.13..x.14..x
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`%K nonn
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`%O 1,4
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`%A _R. H. Hardin_ Aug 23 2012
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