A209005 Number of n-bead necklaces labeled with numbers -6..6 not allowing reversal, with sum zero and first and second differences in -6..6.

1, 2, 7, 26, 137, 923, 6261, 43228, 293991, 1993292, 13620471, 94043892, 656241875

Offset

1,2

Comments

Column 6 of A209007.

Links

Table of n, a(n) for n=1..13.

Example

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

Crossrefs

Sequence in context: A358493 A341900 A300049 * A361242 A068870 A345682

Adjacent sequences: A209002 A209003 A209004 * A209006 A209007 A209008

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved