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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
0

%I #5 Aug 25 2012 05:56:47

%S 1,1,1,4,50,458,15485,234217,14296434,297246092,26970790176

%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

%C Row 6 of A215788

%e Some solutions for n=5

%e ..0..x..1..x..4....0..x..1..x..2....0..x..1..x..4....0..x..1..x..2

%e ..x..2..x..5..x....x..3..x..4..x....x..2..x..5..x....x..3..x..4..x

%e ..3..x..6..x..8....5..x..6..x..7....3..x..6..x..8....5..x..6..x..8

%e ..x..7..x.10..x....x..8..x..9..x....x..7..x..9..x....x..7..x..9..x

%e ..9..x.11..x.13...10..x.11..x.13...10..x.11..x.13...10..x.11..x.12

%e ..x.12..x.14..x....x.12..x.14..x....x.12..x.14..x....x.13..x.14..x

%K nonn

%O 1,4

%A _R. H. Hardin_ Aug 23 2012