A209340 Number of n-bead necklaces labeled with numbers -4..4 allowing reversal, with sum zero with no three beads in a row equal.

1, 5, 12, 72, 400, 2698, 18646, 136000, 1013342, 7713270, 59569974, 465894736, 3681136600, 29342106638

Offset

1,2

Comments

Column 4 of A209344.

Links

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

Example

Some solutions for n=7:
.-3...-3...-4...-4...-4...-4...-3...-4...-4...-3...-3...-4...-4...-3...-4...-4
.-3...-2....0...-2....1...-2....1...-1...-3...-1....2....1....3...-1...-3....2
..2....1....2....0...-2....0....0....3....3....4....3....3...-2...-2....1...-1
..4....0....2...-1...-3....1...-1....1....2...-1...-1...-3....1...-1....3....4
.-3....2....3....1....3....2....2...-3...-4....2...-2....4....1....0....1...-2
..0....3...-4....2....2....3...-3....3....3...-1...-2...-4...-2....4....3...-2
..3...-1....1....4....3....0....4....1....3....0....3....3....3....3...-1....3

Crossrefs

Sequence in context: A242043 A156236 A209481 * A128323 A202203 A074245

Adjacent sequences: A209337 A209338 A209339 * A209341 A209342 A209343

Keyword

nonn

Author

R. H. Hardin, Mar 06 2012

Status

approved