A209069 Number of n-bead necklaces labeled with numbers -4..4 not allowing reversal, with sum zero and avoiding the pattern z z+1 z+2.

1, 5, 20, 122, 766, 5239, 37108, 271732, 2035161, 15526728, 120213839, 942210714, 7461093141, 59602526850, 479745735803

Offset

1,2

Comments

Column 4 of A209073.

Links

Table of n, a(n) for n=1..15.

Example

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

Crossrefs

Sequence in context: A352743 A054720 A208941 * A301952 A110373 A081067

Adjacent sequences: A209066 A209067 A209068 * A209070 A209071 A209072

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved