A195890 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 <=72

1, 1, 13, 1105, 680115, 3204150229

Offset

1,3

Comments

Column 6 of A195892

Links

Table of n, a(n) for n=1..6.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..4-4......0.0......5-5......4-4.....-1.1......5-5......0.0......4-4
.-3.4-1....4.1-5...-4.5-1...-6.1.5....1.4-5...-6.6.0...-3-1.4....2-2.0
.-1.0.1.0.-4-1.5.0.-1.0.1.0..2.3-5.0..0-5.5.0..1-1.0.0..3.1-4.0.-6.6.0.0

Crossrefs

Sequence in context: A076481 A185834 A264249 * A195520 A128897 A201265

Adjacent sequences: A195887 A195888 A195889 * A195891 A195892 A195893

Keyword

nonn

Author

R. H. Hardin Sep 24 2011

Status

approved