A208968 Number of n-bead necklaces labeled with numbers -6..6 allowing reversal, with sum zero and first and second differences in -6..6.

1, 2, 5, 18, 77, 495, 3186, 21830, 147381, 998124, 6812903, 47032427, 328140226

Offset

1,2

Comments

Column 6 of A208970.

Links

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

Example

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

Crossrefs

Sequence in context: A289655 A189281 A006848 * A338179 A206293 A137861

Adjacent sequences: A208965 A208966 A208967 * A208969 A208970 A208971

Keyword

nonn

Author

R. H. Hardin, Mar 03 2012

Status

approved