A209339 Number of n-bead necklaces labeled with numbers -3..3 allowing reversal, with sum zero with no three beads in a row equal.

1, 4, 7, 35, 145, 770, 4029, 22739, 130282, 766177, 4566523, 27587850, 168340643, 1036444786, 6429150260, 40144480583

Offset

1,2

Comments

Column 3 of A209344.

Links

Table of n, a(n) for n=1..16.

Example

Some solutions for n=8:
.-3...-3...-3...-3...-3...-3...-2...-3...-3...-3...-3...-3...-3...-3...-3...-3
..1....0...-2...-2....0....1....0....0...-1...-2...-1...-2....0....0...-2...-2
.-2...-1....1....1....0....1....2...-1...-2....2....0....2...-1....0...-2....0
..1....3....2....1...-3...-2...-1...-1....2....1....3....3...-2...-1....3....0
..0....0....2....0....1...-2....0....1....2....3....1....2....1....2....2....2
.-2....3...-2...-3....0....2....1...-2....0...-3...-2...-3....2....0....1...-1
..3...-3...-1....3....2....1...-2....3....0...-1....3....2....0....1....0....2
..2....1....3....3....3....2....2....3....2....3...-1...-1....3....1....1....2

Crossrefs

Cf. A209344.

Sequence in context: A283819 A124624 A209480 * A212500 A302198 A279830

Adjacent sequences: A209336 A209337 A209338 * A209340 A209341 A209342

Keyword

nonn

Author

R. H. Hardin, Mar 06 2012

Status

approved