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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
1, 35, 1050, 210210, 14294280, 5703417720, 577185873264, 337653735859440, 43364386933948080, 32436561426593163840, 4886336289191784467040, 4340695403565368534887200, 733267473530864041786302000
OFFSET
1,2
COMMENTS
Column 7 of A215297
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin Aug 07 2012
STATUS
approved