A195641 Number of lower triangles of an n X n 0..5 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, 5536654, 4102276124, 10576325574496, 96132191056438654, 3112190512707436846248, 361888107612909923618319047, 152218183506656720143679173709254, 233008581159686014846657554273887832751

Offset

1,3

Links

Table of n, a(n) for n=1..14.

Example

Some solutions for n=5:
..1..........1..........1..........1..........1..........1..........1
..0.2........1.1........0.2........0.2........2.0........1.1........0.2
..0.1.2......0.1.2......0.2.1......2.1.0......2.1.0......0.1.2......1.0.2
..3.1.0.0....2.1.1.0....4.0.0.0....1.0.2.1....0.3.1.0....2.2.0.0....2.1.0.1
..1.0.1.2.1..1.1.0.2.1..0.0.2.2.1..1.1.1.1.1..0.0.2.2.1..1.0.1.2.1..1.1.1.1.1

Crossrefs

Column 5 of A195644.

Sequence in context: A071381 A195639 A195640 * A195642 A195643 A195638

Adjacent sequences: A195638 A195639 A195640 * A195642 A195643 A195644

Keyword

nonn

Author

R. H. Hardin, Sep 21 2011

Extensions

a(12)-a(14) from Andrew Howroyd, May 16 2020

Status

approved