A221618 Number of n X n arrays with each row a permutation of 1..n having at least as many downsteps as the preceding row

1, 3, 112, 85035, 3451956516, 7575106427737240, 2031241364747667201263520, 57096186419355436503540544000542003, 350680349722258761627197454626353435730368352560

Offset

1,2

Comments

Diagonal of A221623

Links

R. H. Hardin, Table of n, a(n) for n = 1..12

Example

Some solutions for n=3
..1..2..3....1..2..3....3..1..2....3..1..2....2..1..3....1..2..3....2..3..1
..2..1..3....3..1..2....3..1..2....2..3..1....1..3..2....1..3..2....3..1..2
..3..2..1....3..2..1....2..3..1....3..1..2....2..3..1....3..2..1....3..1..2

Crossrefs

Sequence in context: A054330 A024043 A199640 * A300814 A075051 A139929

Adjacent sequences: A221615 A221616 A221617 * A221619 A221620 A221621

Keyword

nonn

Author

R. H. Hardin Jan 21 2013

Status

approved