A208991 Number of n-bead necklaces labeled with numbers -6..6 not allowing reversal, with sum zero and first differences in -6..6.

1, 4, 15, 95, 683, 5404, 44209, 371893, 3189719, 27799922, 245493567, 2192108831, 19760508059, 179591215329

Offset

1,2

Comments

Column 6 of A208993.

Links

Table of n, a(n) for n=1..14.

Example

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

Crossrefs

Sequence in context: A013193 A040025 A366697 * A109365 A352415 A079128

Adjacent sequences: A208988 A208989 A208990 * A208992 A208993 A208994

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved