A208999 Number of n-bead necklaces labeled with numbers -n..n not allowing reversal, with sum zero and first and second differences in -n..n.

1, 1, 3, 10, 71, 923, 14701, 279721, 6025413, 146448941, 3999932289

Offset

1,3

Comments

Diagonal of A209007.

Links

Table of n, a(n) for n=1..11.

Example

Some solutions for n=6:
.-3...-5...-2...-2...-5...-2...-4...-5...-2...-2...-3...-4...-2...-4...-3...-5
.-1...-2...-1...-2...-5...-2...-4...-3...-2...-2...-1....0....0...-4....0...-4
..0....4...-1....2....1....3...-1....3....1...-1....1....4...-2....2....1....2
..4....4....2....2....5....2....3....4....3....0....1....4....1....5....3....4
..2....2....0...-1....3...-1....4....2....1....2....1...-1....2....2...-1....4
.-2...-3....2....1....1....0....2...-1...-1....3....1...-3....1...-1....0...-1

Crossrefs

Cf. A209007.

Sequence in context: A002499 A047833 A047834 * A181075 A136507 A334211

Adjacent sequences: A208996 A208997 A208998 * A209000 A209001 A209002

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved