A195642 Number of lower triangles of an n X n 0..6 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, 4116036800, 10694128575819, 98630958757213465, 3267417937114919996252

Offset

1,3

Comments

Column 6 of A194644

Links

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

Example

Some solutions for n=6
..1............1............1............1............1............1
..1.1..........1.1..........0.2..........2.0..........0.2..........2.0
..2.1.0........2.1.0........2.1.0........2.1.0........2.1.0........2.1.0
..2.0.0.2......1.2.1.0......0.0.3.1......0.2.1.1......0.1.3.0......0.3.1.0
..0.0.2.1.2....1.0.2.0.2....1.0.1.1.2....0.1.2.2.0....1.0.1.1.2....1.0.2.1.1
..0.3.2.0.0.1..0.1.1.3.0.1..2.2.0.1.0.1..1.1.1.0.2.1..2.1.0.2.0.1..0.1.1.2.1.1

Crossrefs

Sequence in context: A195639 A195640 A195641 * A195643 A195638 A041951

Adjacent sequences: A195639 A195640 A195641 * A195643 A195644 A195645

Keyword

nonn

Author

R. H. Hardin Sep 21 2011

Status

approved