A208803 Number of n-bead necklaces labeled with numbers -6..6 allowing reversal, with sum zero and three times sum of squares <= n*(6)*(6+1).

1, 4, 17, 136, 1073, 10372, 105147, 1111859, 11969879, 132339307, 1483656527, 16847824961, 193620920219, 2242918877972, 26215739119341, 308466499187272, 3650953780091983, 43460429194159752, 519724194908777521, 6242649556702436466

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..40

Example

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

Crossrefs

Column 6 of A208805.

Sequence in context: A337521 A032325 A032335 * A156076 A041026 A072755

Adjacent sequences: A208800 A208801 A208802 * A208804 A208805 A208806

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Extensions

a(13)-a(20) from Andrew Howroyd, Mar 02 2017

Status

approved