A267988 Number of nX2 arrays containing 2 copies of 0..n-1 with row sums and column sums nondecreasing.

1, 4, 21, 189, 1941, 28032, 448157, 8951313, 194183520, 4923018003, 134463192215

Offset

1,2

Comments

Column 2 of A267990.

Links

Table of n, a(n) for n=1..11.

Example

Some solutions for n=6
..0..1....0..4....3..0....0..3....0..0....1..1....0..1....1..3....1..3....0..3
..2..2....4..1....3..1....0..5....4..1....0..4....3..0....0..4....0..5....3..2
..5..0....0..5....4..0....1..4....1..5....0..5....2..3....0..5....3..2....5..0
..1..5....2..3....2..4....2..3....4..2....2..4....1..4....3..2....4..1....1..4
..3..4....2..3....1..5....1..5....3..3....3..3....4..2....1..5....5..0....1..4
..4..3....1..5....2..5....4..2....2..5....2..5....5..5....4..2....2..4....5..2

Crossrefs

Cf. A267990.

Sequence in context: A158108 A158258 A065527 * A360630 A041667 A377828

Adjacent sequences: A267985 A267986 A267987 * A267989 A267990 A267991

Keyword

nonn

Author

R. H. Hardin, Jan 23 2016

Status

approved