A215869 Number of permutations of 0..floor((n*9-2)/2) on odd squares of an nX9 array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing.

1, 14, 290, 11694, 307874, 14296434, 386699176, 18255280444, 494952307400, 23397688110992, 634501639410480, 29997930933948284, 813501010455768664, 38461009542931961924, 1043008988814913191696, 49311812528326463481148

Offset: 1

Author

R. H. Hardin Aug 25 2012

Keywords

• nonn

Comments

Column 9 of A215870

Examples

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

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)