A188363 Number of arrangements of 8 numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero.

1477, 37269, 262925, 1264985, 3882729, 11535493, 25217201, 55520361, 106276821, 198605017, 325986813, 569829701, 864406561

Offset: 1

Author

R. H. Hardin Mar 28 2011

Keywords

• nonn

Comments

Row 7 of A188358

Examples

			Some solutions for n=4
.-4...-4...-2...-4...-2...-1...-2...-3...-2...-1...-3...-4...-1...-4...-3...-3
.-4...-3...-3...-3...-4...-4...-3...-3...-3...-4...-4...-4...-3...-3...-4...-4
..2....4....0....3....3....4...-4....0....0...-2....0....4...-2....0...-1....1
.-2....2....3...-1....2....1....4....3....2....0....2...-3....4...-1....4....4
..4....4....2...-3...-2....0....0...-3....3...-3....3...-4...-3....3....0....2
..1...-4....4....1...-1...-1....2....0....0...-4...-2....0...-1...-1...-1...-2
..0...-3...-4....0....0...-4....1....0....3....3....2....0...-4...-2...-4....4
..4....4....1....3...-2...-1...-4...-4...-4...-4...-4...-2...-1....4....4...-2