A195519 Number of lower triangles of an n X n -5..5 array with all row and column sums zero

1, 1, 11, 671, 401565, 2106810049, 103074513713971, 47878816111749257161

Offset

1,3

Comments

Column 5 of A195522

Links

Table of n, a(n) for n=1..8.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..2-2......5-5......4-4......0.0......5-5.....-2.2......0.0.....-5.5
.-4.4.0...-1.3-2...-5.4.1...-1.2-1...-1.3-2....4.0-4...-1.4-3....3-5.2
..2-2.0.0.-4.2.2.0..1.0-1.0..1-2.1.0.-4.2.2.0.-2-2.4.0..1-4.3.0..2.0-2.0

Crossrefs

Sequence in context: A211401 A036933 A195889 * A218716 A232355 A301732

Adjacent sequences: A195516 A195517 A195518 * A195520 A195521 A195522

Keyword

nonn

Author

R. H. Hardin Sep 20 2011

Status

approved