A202544 Number of n X n nonnegative integer arrays with each row and column an ascent sequence (interior element no greater than one plus up-steps preceding it)

1, 2, 18, 1094, 658492, 5534917394, 876480920594230, 3399581643395993926522

Offset

1,2

Comments

Diagonal of A202549

Links

Table of n, a(n) for n=1..8.

Example

Some solutions for n=5
..0..0..0..0..0....0..0..0..0..0....0..0..0..0..0....0..0..0..0..0
..0..0..0..0..0....0..0..0..0..1....0..0..0..0..1....0..0..0..1..1
..0..0..1..1..1....0..1..0..1..2....0..1..0..1..0....0..0..1..1..0
..0..0..1..2..1....0..0..1..2..3....0..1..1..0..1....0..0..1..1..1
..0..1..1..1..2....0..1..2..2..2....0..0..0..1..2....0..0..0..0..1

Crossrefs

Sequence in context: A013040 A268051 A268074 * A203421 A139111 A090766

Adjacent sequences: A202541 A202542 A202543 * A202545 A202546 A202547

Keyword

nonn

Author

R. H. Hardin Dec 20 2011

Status

approved