A208821 Number of n-bead necklaces labeled with numbers -4..4 allowing reversal, with sum zero.

1, 5, 13, 75, 415, 2821, 19657, 144871, 1090645, 8392423, 65527045, 518173267, 4139803293, 33366946637

Offset: 1

Author

R. H. Hardin, Mar 01 2012

Keywords

• nonn

Comments

Column 4 of A208825.

Examples

			All solutions for n=3:
.-2...-1....0...-4...-2...-3...-3...-3...-1...-4...-2...-2...-4
.-1....0....0....1....0....0...-1....1...-1....0...-2....1....2
..3....1....0....3....2....3....4....2....2....4....4....1....2