A209477 Number of n-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.

1, 3, 7, 72, 866, 16660, 401634, 11891268, 413867410, 16583242015

Offset

1,2

Comments

Diagonal of A209485.

Links

Table of n, a(n) for n=1..10.

Example

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

Crossrefs

Sequence in context: A113841 A128072 A094008 * A209336 A078552 A091259

Adjacent sequences: A209474 A209475 A209476 * A209478 A209479 A209480

Keyword

nonn

Author

R. H. Hardin, Mar 09 2012

Status

approved