A209006 Number of n-bead necklaces labeled with numbers -7..7 not allowing reversal, with sum zero and first and second differences in -7..7.

1, 2, 7, 38, 243, 1854, 14701, 116960, 916381, 7170239, 56496359, 449785468, 3619072169

Offset

1,2

Comments

Column 7 of A209007.

Links

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

Example

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

Crossrefs

Sequence in context: A275621 A094431 A256032 * A168492 A346646 A032109

Adjacent sequences: A209003 A209004 A209005 * A209007 A209008 A209009

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved