A215295 Number of permutations of 0..floor((n*5-2)/2) on odd squares of an nX5 array such that each row and column of odd squares is increasing.

1, 10, 70, 2100, 23100, 1051050, 14294280, 814773960, 12547518984, 824551247520, 13781785137120, 999179422441200, 17699749768958400, 1379105502831342000, 25513451802379827000, 2100607531729272423000, 40191624107086745693400

Offset: 1

Author

R. H. Hardin Aug 07 2012

Keywords

• nonn

Comments

Column 5 of A215297

Examples

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

Links

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

Formula

f3=floor((n+1)/2)

f4=floor(n/2)

a(n) = A060854(2,f3)*A060854(3,f4)*binomial(2*f3+3*f4,2*f3)