A209107 Number of n-bead necklaces labeled with numbers -n..n not allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.

1, 3, 11, 120, 1683, 32802, 802125, 23766209, 827695021, 33165786247

Offset

1,2

Comments

Diagonal of A209115.

Links

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

Example

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

Crossrefs

Sequence in context: A036930 A198085 A319749 * A015047 A339326 A102847

Adjacent sequences: A209104 A209105 A209106 * A209108 A209109 A209110

Keyword

nonn

Author

R. H. Hardin, Mar 05 2012

Status

approved