A215787 Number of permutations of 0..floor((n*9-1)/2) on even squares of an nX9 array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing.

1, 14, 462, 11694, 530429, 14296434, 673507749, 18255280444, 862827082115, 23397688110992, 1106178923600669, 29997930933948284, 1418251919293188195, 38461009542931961924, 1818375422885354065137, 49311812528326463481148

Offset: 1

Author

R. H. Hardin Aug 23 2012

Keywords

• nonn

Comments

Column 9 of A215788

Examples

			Some solutions for n=4
..0..x..1..x..3..x..6..x..8....0..x..1..x..2..x..6..x.11
..x..2..x..5..x.10..x.13..x....x..3..x..5..x..8..x.12..x
..4..x..7..x.11..x.14..x.15....4..x..7..x.10..x.14..x.16
..x..9..x.12..x.16..x.17..x....x..9..x.13..x.15..x.17..x
		

Links

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

Formula

Empirical: a(n) = 1385*a(n-2) -131648*a(n-4) -318070*a(n-6) -4160916*a(n-8) -1097892*a(n-10) +648*a(n-12)