A195643 Number of lower triangles of an n X n 0..7 array with all row sums equal to the length of the row and all column sums equal to the length of the column

1, 1, 3, 19, 391, 25532, 5539434, 4116290300, 10699674783969, 98827025484631957, 3284291571314714878300

Offset

1,3

Comments

Column 7 of A194644

Links

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

Example

Some solutions for n=7
..1..............1..............1..............1..............1
..1.1............0.2............2.0............2.0............2.0
..0.3.0..........0.3.0..........3.0.0..........2.1.0..........2.1.0
..4.0.0.0........2.1.1.0........0.2.2.0........1.3.0.0........2.2.0.0
..0.2.2.0.1......2.0.1.1.1......1.1.2.0.1......1.2.2.0.0......0.1.0.3.1
..1.0.1.0.2.2....2.0.2.0.2.0....0.3.0.1.2.0....0.0.2.4.0.0....0.1.4.0.1.0
..0.0.2.4.0.0.1..0.0.1.3.0.2.1..0.0.1.3.0.2.1..0.0.1.0.3.2.1..0.1.1.1.1.2.1

Crossrefs

Sequence in context: A195640 A195641 A195642 * A195638 A041951 A365362

Adjacent sequences: A195640 A195641 A195642 * A195644 A195645 A195646

Keyword

nonn

Author

R. H. Hardin Sep 21 2011

Status

approved