A208800 Number of n-bead necklaces labeled with numbers -3..3 allowing reversal, with sum zero and three times sum of squares <= n*(3)*(3+1).

1, 3, 5, 24, 99, 518, 2782, 15485, 88835, 524548, 3150568, 19343270, 119596665, 746620321, 4690323708, 29666561267, 188933152165, 1210058865663, 7790312435430, 50365101710864, 326846325778607, 2128466374313259, 13905579793860582, 91122902226298461, 598778033049098861

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..50

Example

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

Crossrefs

Column 3 of A208805.

Sequence in context: A286427 A290509 A347947 * A356274 A249935 A364961

Adjacent sequences: A208797 A208798 A208799 * A208801 A208802 A208803

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Extensions

a(17)-a(25) from Andrew Howroyd, Mar 02 2017

Status

approved