A215296 Number of permutations of 0..floor((n*7-2)/2) on odd squares of an nX7 array such that each row and column of odd squares is increasing

1, 35, 1050, 210210, 14294280, 5703417720, 577185873264, 337653735859440, 43364386933948080, 32436561426593163840, 4886336289191784467040, 4340695403565368534887200, 733267473530864041786302000

Offset

1,2

Comments

Column 7 of A215297

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(3,f3)*A060854(4,f4)*binomial(3*f3+4*f4,3*f3)

Example

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

Crossrefs

Sequence in context: A210313 A049395 A278723 * A209180 A115492 A187538

Adjacent sequences: A215293 A215294 A215295 * A215297 A215298 A215299

Keyword

nonn

Author

R. H. Hardin Aug 07 2012

Status

approved