A209110 Number of n-bead necklaces labeled with numbers -3..3 not allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.

1, 4, 11, 55, 261, 1373, 7377, 41256, 235639, 1372782, 8114465, 48564722, 293656843, 1791382922, 11011083783, 68131049950, 424018776003

Offset

1,2

Comments

Column 3 of A209115.

Links

Table of n, a(n) for n=1..17.

Example

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

Crossrefs

Sequence in context: A027042 A051770 A262006 * A363664 A282742 A032181

Adjacent sequences: A209107 A209108 A209109 * A209111 A209112 A209113

Keyword

nonn

Author

R. H. Hardin, Mar 05 2012

Status

approved