A211885 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, and containing the value n(n+1)/2-2

0, 2, 8, 26, 66, 141, 267, 463, 751

Offset

1,2

Comments

Column 1 of A211888

Links

Table of n, a(n) for n=1..9.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.0......1.2......1.2......1.2
..3.4.1....3.4.5....3.4.5....3.4.5....2.3.4....3.4.5....3.4.5....3.4.5
..5.6.7.8..6.7.8.9..6.7.3.8..2.6.7.8..5.6.7.8..6.7.8.3..6.3.7.8..6.7.8.1

Crossrefs

Sequence in context: A100504 A327600 A099416 * A101696 A155861 A212140

Adjacent sequences: A211882 A211883 A211884 * A211886 A211887 A211888

Keyword

nonn

Author

R. H. Hardin Apr 24 2012

Status

approved