A215786 Number of permutations of 0..floor((n*8-1)/2) on even squares of an nX8 array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing.

1, 5, 110, 932, 26451, 234217, 6812794, 60485308, 1761748159, 15643423061, 455678075546, 4046220880948, 117863060852067, 1046572601513969, 30485799411892266, 270700616010831020, 7885286478349158743

Offset: 1

Author

R. H. Hardin Aug 23 2012

Keywords

• nonn

Comments

Column 8 of A215788

Examples

			Some solutions for n=4
..0..x..1..x..3..x..7..x....0..x..1..x..2..x..3..x....0..x..1..x..2..x..5..x
..x..2..x..4..x..9..x.10....x..4..x..6..x..7..x..8....x..3..x..4..x..7..x.11
..5..x..6..x.11..x.12..x....5..x..9..x.10..x.12..x....6..x..8..x..9..x.13..x
..x..8..x.13..x.14..x.15....x.11..x.13..x.14..x.15....x.10..x.12..x.14..x.15
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 272*a(n-2) -3439*a(n-4) -3336*a(n-6) +140*a(n-8)