A209071 Number of n-bead necklaces labeled with numbers -6..6 not allowing reversal, with sum zero and avoiding the pattern z z+1 z+2.

1, 7, 42, 366, 3378, 33469, 344618, 3660116, 39772437, 440146892, 4943305065, 56200679500, 645543627296

Offset

1,2

Comments

Column 6 of A209073.

Links

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

Example

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

Crossrefs

Cf. A209073.

Sequence in context: A218124 A048862 A208943 * A174224 A278571 A133669

Adjacent sequences: A209068 A209069 A209070 * A209072 A209073 A209074

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved