A181200 a(n) = 0!*1!*2!*...*(n-1)! *(n^2)! *(n*(n-1))^2 / 2*n!*(n+1)!*...*(2*n-1)!

0, 4, 756, 1729728, 140229804000, 752239365180732000, 419014989521191873479589920, 34623595988556658225393154134784716800, 571228532851873223553288547443139274046846826752000

Offset

1,2

Comments

(Empirical) Number of n X n matrices containing a defective permutation of 1..n*n in strictly increasing order rowwise and columnwise, with one permutation value omitted and one repeated (see example)

Diagonal of A181204

Links

R. H. Hardin, Table of n, a(n) for n=1..22

Example

Some solutions for 3X3
..2..3..5....1..2..5....1..2..6....1..3..4....1..3..4....1..2..4....1..3..5
..4..6..7....3..4..6....3..4..8....2..5..8....2..6..7....2..5..7....2..4..6
..5..8..9....4..7..9....6..7..9....4..6..9....5..7..9....3..6..9....6..7..8

Crossrefs

Sequence in context: A268838 A292306 A319943 * A308141 A284813 A306254

Adjacent sequences: A181197 A181198 A181199 * A181201 A181202 A181203

Keyword

nonn

Author

R. H. Hardin Oct 10 2010

Status

approved