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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, 1, 3, 19, 391, 25532, 5536654, 4102276124, 10576325574496, 96132191056438654, 3112190512707436846248, 361888107612909923618319047, 152218183506656720143679173709254, 233008581159686014846657554273887832751
OFFSET
1,3
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 21 2011
EXTENSIONS
a(12)-a(14) from Andrew Howroyd, May 16 2020
STATUS
approved