A182293 Number of lower triangular n X n arrays of integers 0 upwards introduced in row major order, with each element unique in its row and column.

1, 2, 22, 2418, 4276864

Offset

1,2

Links

Table of n, a(n) for n=1..5.

Example

Some solutions for n=4:
..0........0........0........0........0........0........0........0
..1.2......1.2......1.0......1.2......1.2......1.2......1.2......1.0
..3.4.1....3.4.5....2.3.4....3.0.4....3.4.5....3.1.4....3.4.5....2.3.4
..5.3.4.2..5.1.4.3..5.2.0.1..4.5.3.6..5.6.4.2..2.5.3.4..6.5.7.0..5.6.3.2

Crossrefs

Sequence in context: A113761 A319620 A054349 * A222000 A261400 A113930

Adjacent sequences: A182290 A182291 A182292 * A182294 A182295 A182296

Keyword

nonn,more

Author

R. H. Hardin, Apr 24 2012

Status

approved