A208941 Number of n-bead necklaces labeled with numbers -4..4 not allowing reversal, with sum zero with no three beads in a row equal.

1, 5, 20, 122, 766, 5238, 37044, 270832, 2024738, 15417296, 119124324, 931714740, 7362145488, 58683599062, 471302764880

Offset

1,2

Comments

Column 4 of A208945.

Links

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

Example

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

Crossrefs

Sequence in context: A352743 A054720 A374658 * A209069 A301952 A110373

Adjacent sequences: A208938 A208939 A208940 * A208942 A208943 A208944

Keyword

nonn

Author

R. H. Hardin, Mar 03 2012

Status

approved