A195525 Number of lower triangles of a 7X7 -n..n array with all row and column sums zero.

505623, 839301197, 122092290831, 5151383545261, 103074513713971, 1252997799222737, 10665939121760907, 69488770600802237, 367679036207885407, 1647079991451268941, 6438544930173240123, 22466897655527435065

Offset: 1

Author

R. H. Hardin Sep 20 2011

Keywords

• nonn

Comments

Row 7 of A195522

Examples

			Some solutions for n=4
..0..............0..............0..............0..............0
.-4.4...........-4.4............3-3...........-2.2...........-4.4
..1.2-3..........2-3.1..........3-2-1.........-2.1.1.........-2.0.2
..4-1-1-2.......-3-3.3.3........2-1.1-2.......-4-1.1.4........4.3-3-4
.-1-1.2.2-2......3-3-1-1.2.....-2.2.1.3-4......3-2.2.0-3.....-1-4-3.4.4
.-2-3.2-1.3.1...-1.3-3.0-3.4...-2.3.2-4.4-3....2-4.0-1.2.1....1.0.0.3-3-1
..2-1.0.1-1-1.0..3.2.0-2.1-4.0.-4.1-3.3.0.3.0..3.4-4-3.1-1.0..2-3.4-3-1.1.0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..14