A195892 T(n,k) = 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 <= 2k^2.

1, 1, 1, 1, 1, 3, 1, 1, 5, 15, 1, 1, 7, 65, 83, 1, 1, 9, 175, 1349, 591, 1, 1, 11, 369, 14831, 90013, 5281, 1, 1, 13, 671, 68551, 4857647, 17612909, 56249, 1, 1, 15, 1105, 241221, 65530899, 5181491667, 7690681987, 704129, 1, 1, 17, 1695, 680115, 584257875

Offset

1,6

Comments

Table starts

......1..........1..........1............1.........1......1....1..1.1.1

......1..........1..........1............1.........1......1....1..1.1

......3..........5..........7............9........11.....13...15.17

.....15.........65........175..........369.......671...1105.1695

.....83.......1349......14831........68551....241221.680115

....591......90013....4857647.....65530899.584257875

...5281...17612909.5181491667.314737269521

..56249.7690681987

.704129

Links

R. H. Hardin, Table of n, a(n) for n = 1..52

Example

Some solutions for n=5 k=4
..0..........0..........0..........0..........0..........0..........0
.-1.1........1-1.......-4.4........3-3........1-1........2-2........3-3
.-2.1.1.....-2.4-2......3-3.0......0.3-3.....-2.4-2.....-4.3.1......0-1.1
..0-1-1.2...-2-1.2.1....1-1-3.3...-1-1.0.2....0-2-1.3....1-2.0.1....1.0-1.0
..3-1.0-2.0..3-2.0-1.0..0.0.3-3.0.-2.1.3-2.0..1-1.3-3.0..1.1-1-1.0.-4.4.0.0.0

Crossrefs

Sequence in context: A335333 A341470 A293796 * A195522 A273169 A273167

Adjacent sequences: A195889 A195890 A195891 * A195893 A195894 A195895

Keyword

nonn,tabl

Author

R. H. Hardin, Sep 24 2011

Status

approved