A209113 Number of n-bead necklaces labeled with numbers -6..6 not allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.

1, 7, 41, 362, 3325, 32802, 336055, 3552027, 38413793, 423087907, 4729090301, 53509230007

Offset

1,2

Comments

Column 6 of A209115.

Links

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

Example

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

Crossrefs

Sequence in context: A353992 A181441 A290044 * A146991 A356129 A053676

Adjacent sequences: A209110 A209111 A209112 * A209114 A209115 A209116

Keyword

nonn

Author

R. H. Hardin, Mar 05 2012

Status

approved