A195521 Number of lower triangles of an n X n -7..7 array with all row and column sums zero.
1, 1, 15, 1695, 2563933, 46387885537, 10665939121760907, 31749804821289929290261
Offset: 1
Keywords
Examples
Some solutions for n=4 ..0........0........0........0........0........0........0........0 .-1.1......2-2.....-4.4......7-7.....-2.2.....-3.3......3-3......6-6 ..3-1-2....1.4-5....3-5.2...-4.0.4...-4.1.3....3-3.0....2.1-3...-2.5-3 .-2.0.2.0.-3-2.5.0..1.1-2.0.-3.7-4.0..6-3-3.0..0.0.0.0.-5.2.3.0.-4.1.3.0
Comments