A209072 Number of n-bead necklaces labeled with numbers -7..7 not allowing reversal, with sum zero and avoiding the pattern z z+1 z+2.

1, 8, 56, 563, 6006, 68723, 817594, 10030238, 125899533, 1609360719, 20877938573, 274173012896

Offset

1,2

Comments

Column 7 of A209073.

Links

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

Example

Some solutions for n=6:
.-7...-5...-7...-7...-7...-6...-7...-6...-5...-7...-5...-7...-6...-6...-6...-5
.-6....0....4....4...-6....3...-2....5....0....3...-3...-4....7...-2....5....5
..1...-4....6....2....4....6....3....5....4....2....6....2...-5....1...-4...-3
..1....3...-4....0....7....2....4....0....2....0....2....6....2....4....1....5
..4...-1...-2...-3....4...-4....0...-1...-3....1....1....5....4....5....3....0
..7....7....3....4...-2...-1....2...-3....2....1...-1...-2...-2...-2....1...-2

Crossrefs

Sequence in context: A009107 A209665 A208944 * A133671 A326239 A154411

Adjacent sequences: A209069 A209070 A209071 * A209073 A209074 A209075

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved