A188356 Number of arrangements of n+1 numbers x(i) in -7..7 with the sum of x(i)*x(i+1) equal to zero.

29, 435, 1569, 22583, 163745, 2295051, 25217201, 355442823, 4602176797, 65556183495, 902973314217, 12966307902587, 183476638021301, 2650029026701115, 38023581868527461, 551634055112635223

Offset: 1

Author

R. H. Hardin Mar 28 2011

Keywords

• nonn

Comments

Column 7 of A188358

Examples

			Some solutions for n=4
.-6...-1....2...-1...-3....3....7...-1....0...-3...-1....3...-7....7....3...-1
..0....0....0....0...-5....0...-5....0...-6....6...-6....2....0...-3....0....0
..3....1....2....5....3...-5...-3....2....1....2...-1....0...-3...-3....0....2
..1....4....6....4....0....0....5...-5....3...-3...-6....3...-7....6....0....0
.-3...-1...-2...-5...-2...-5....7...-2....1...-4....3...-2....3....5...-5...-5