A221627 Number of 5Xn arrays with each row a permutation of 1..n having at least as many downsteps as the preceding row

1, 6, 1818, 1130256, 3451956516, 21241004664348, 332469512259607296, 9510929074212911717760, 521875340203828179569609700, 47602100904962622927705491352020, 7181861163349151796773697873026037828

Offset

1,2

Comments

Row 5 of A221623

Links

R. H. Hardin, Table of n, a(n) for n = 1..13

Example

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

Crossrefs

Sequence in context: A258900 A357760 A250393 * A160301 A209496 A372525

Adjacent sequences: A221624 A221625 A221626 * A221628 A221629 A221630

Keyword

nonn

Author

R. H. Hardin Jan 21 2013

Status

approved