A211886 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)/2-3

0, 2, 19, 236, 1726, 8471, 31732

Offset

1,2

Comments

Column 2 of A211888

Links

Table of n, a(n) for n=1..7.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2
..3.4.5....3.4.5....3.4.5....3.4.5....3.4.2....3.4.5....3.4.2....2.0.3
..6.7.3.1..2.6.7.0..6.7.2.1..6.1.3.7..5.6.4.7..6.7.1.0..5.6.7.0..4.5.6.7

Crossrefs

Sequence in context: A232525 A024227 A106945 * A125632 A124125 A234505

Adjacent sequences: A211883 A211884 A211885 * A211887 A211888 A211889

Keyword

nonn

Author

R. H. Hardin Apr 24 2012

Status

approved