A209342 Number of n-bead necklaces labeled with numbers -6..6 allowing reversal, with sum zero with no three beads in a row equal.

1, 7, 24, 205, 1724, 16968, 172610, 1830872, 19860306, 219630346, 2464760150, 28002352120

Offset

1,2

Comments

Column 6 of A209344.

Links

Table of n, a(n) for n=1..12.

Example

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

Crossrefs

Sequence in context: A198055 A012761 A209483 * A203117 A197791 A009652

Adjacent sequences: A209339 A209340 A209341 * A209343 A209344 A209345

Keyword

nonn

Author

R. H. Hardin, Mar 06 2012

Status

approved