A211887 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)/2-4

0, 0, 22, 957, 23267, 285622, 2223733

Offset

1,3

Comments

Column 3 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......1.0......1.2......1.2......1.2......1.2......1.2
..3.4.5....3.4.1....2.1.3....3.4.0....3.0.4....3.0.4....3.4.1....2.3.4
..2.5.1.6..5.1.6.2..4.3.5.6..5.6.7.4..2.3.5.6..4.3.5.6..5.1.6.7..5.6.0.7

Crossrefs

Sequence in context: A322930 A200575 A102995 * A041927 A041924 A160139

Adjacent sequences: A211884 A211885 A211886 * A211888 A211889 A211890

Keyword

nonn

Author

R. H. Hardin Apr 24 2012

Status

approved