A208804 Number of n-bead necklaces labeled with numbers -7..7 allowing reversal, with sum zero and three times sum of squares <= n*(7)*(7+1).

1, 5, 22, 201, 1827, 21227, 243678, 2951235, 37509753, 473996108, 6076893848, 80987915371, 1065626336007, 14153929259801, 193667696486438, 2610764121932745, 35428434842511617, 493224952143247713, 6763266087728449466, 93152055287986212052

Offset

1,2

Links

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

Example

Some solutions for n=6:
.-4...-5...-5...-5...-6...-7...-3...-5...-3...-5...-4...-5...-5...-5...-5...-3
.-1...-3....0....1...-2....3...-2...-3...-3...-3...-3....0...-2...-2....1...-2
.-3...-3...-2...-4....4...-3....0....2...-2....1...-3...-5....1...-3...-4....0
..7....2....6....0...-3....0...-3...-4....5....7....4....4...-4....5....5....5
..1....3....1....4....2....4....3....6...-1...-3....4....2....6....3....0...-1
..0....6....0....4....5....3....5....4....4....3....2....4....4....2....3....1

Crossrefs

Column 7 of A208805.

Sequence in context: A129437 A048252 A356773 * A066866 A115657 A066865

Adjacent sequences: A208801 A208802 A208803 * A208805 A208806 A208807

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Extensions

a(12)-a(20) from Andrew Howroyd, Mar 02 2017

Status

approved