A195640 Number of lower triangles of an n X n 0..4 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, 25428, 5422820, 3868544673, 9374373474455, 78121590505558308, 2262375741577763676620, 229653423345084153764141412, 82310438395814327559991274396712, 104810153877236566878585186368604425875

Offset

1,3

Links

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

Example

Some solutions for n=4:
..1........1........1........1........1........1........1........1
..2.0......0.2......1.1......0.2......0.2......0.2......1.1......2.0
..1.0.2....1.0.2....1.0.2....1.0.2....3.0.0....3.0.0....1.0.2....1.0.2
..0.3.0.1..2.1.0.1..1.2.0.1..2.1.0.1..0.1.2.1..0.1.2.1..1.2.0.1..0.3.0.1

Crossrefs

Column 4 of A195644.

Sequence in context: A219270 A071381 A195639 * A195641 A195642 A195643

Adjacent sequences: A195637 A195638 A195639 * A195641 A195642 A195643

Keyword

nonn

Author

R. H. Hardin, Sep 21 2011

Extensions

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

Status

approved