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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)
0
1, 2, 18, 1094, 658492, 5534917394, 876480920594230, 3399581643395993926522
OFFSET
1,2
COMMENTS
Diagonal of A202549
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
KEYWORD
nonn
AUTHOR
R. H. Hardin Dec 20 2011
STATUS
approved