A208809 Number of n-bead necklaces labeled with numbers -3..3 not allowing reversal, with sum zero and three times sum of squares <= n*(3)*(3+1).

1, 3, 7, 37, 185, 982, 5491, 30634, 177213, 1046962, 6298375, 38673066, 239176117, 1493154690, 9380538425, 59332570286, 377865591909

Offset

1,2

Comments

Column 3 of A208814.

Links

Table of n, a(n) for n=1..17.

Example

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

Crossrefs

Sequence in context: A308392 A087208 A161675 * A086031 A174734 A152560

Adjacent sequences: A208806 A208807 A208808 * A208810 A208811 A208812

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Status

approved