A209002 Number of n-bead necklaces labeled with numbers -3..3 not allowing reversal, with sum zero and first and second differences in -3..3.

1, 1, 3, 5, 13, 46, 157, 608, 2245, 8184, 30309, 113476, 428729, 1637809, 6309489, 24478530, 95532067, 374703951

Offset

1,3

Comments

Column 3 of A209007.

Links

Table of n, a(n) for n=1..18.

Example

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

Crossrefs

Sequence in context: A128548 A321358 A113606 * A106879 A249762 A264812

Adjacent sequences: A208999 A209000 A209001 * A209003 A209004 A209005

Keyword

nonn,more

Author

R. H. Hardin, Mar 04 2012

Status

approved