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A195885
Number of lower triangles of an n X n integer array with all row and column sums zero and all row and column sums of squares <=2
0
1, 1, 3, 15, 83, 591, 5281, 56249, 704129, 10236185, 170423795, 3211956071, 67925755107, 1599937402631
OFFSET
1,3
COMMENTS
Column 1 of A195892
EXAMPLE
Some solutions for n=4
..0........0........0........0........0........0........0........0
..0.0.....-1.1.....-1.1......0.0.....-1.1......0.0......1-1......1-1
..0.0.0....0.0.0....0.0.0...-1.1.0....0.0.0....0-1.1...-1.1.0....0.0.0
..0.0.0.0..1-1.0.0..1-1.0.0..1-1.0.0..1-1.0.0..0.1-1.0..0.0.0.0.-1.1.0.0
CROSSREFS
Sequence in context: A118356 A074552 A193658 * A115910 A355094 A106569
KEYWORD
nonn
AUTHOR
R. H. Hardin Sep 24 2011
STATUS
approved