A208988 Number of n-bead necklaces labeled with numbers -3..3 not allowing reversal, with sum zero and first differences in -3..3.

1, 2, 5, 16, 59, 253, 1111, 5067, 23483, 110772, 529201, 2557073, 12471501, 61328336, 303723367, 1513583006, 7584498891, 38192683192, 193171464383, 980903632155

Offset

1,2

Comments

Column 3 of A208993.

Links

Table of n, a(n) for n=1..20.

Example

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

Crossrefs

Sequence in context: A087949 A028333 A007747 * A107283 A059237 A369483

Adjacent sequences: A208985 A208986 A208987 * A208989 A208990 A208991

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved