A209065 Number of n-bead necklaces labeled with numbers -n..n not allowing reversal, with sum zero and avoiding the pattern z z+1 z+2.

1, 3, 12, 122, 1722, 33469, 817594, 24194286, 841661871, 33691654098

Offset

1,2

Comments

Diagonal of A209073.

Links

Table of n, a(n) for n=1..10.

Example

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

Crossrefs

Sequence in context: A280248 A067124 A208937 * A124153 A162127 A073987

Adjacent sequences: A209062 A209063 A209064 * A209066 A209067 A209068

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved