A208798 Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and three times sum of squares <= n*(1)*(1+1).

1, 1, 2, 3, 3, 15, 22, 38, 147, 296, 526, 2421, 5017, 10025, 43986, 96951, 202141, 880269, 1993222, 4317765, 18453137, 42777491, 95192956, 400944526, 946008489, 2151685046, 8941940220, 21409059701, 49569448411, 203582329338, 493419056384, 1159647133954

Offset

1,3

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Example

All solutions for n=6:
.-1...-1...-1...-1...-1...-1...-1...-1...-1....0...-1...-1...-1...-1...-1
.-1....0....0....0....0....0....0....0...-1....0...-1....0...-1....0....0
..0....0....0....0...-1....1...-1....0....1....0....0....1....0....1....0
..0....0....0....1....1....0....0....1....0....0....1...-1....1...-1...-1
..1....1....0....0....0...-1....1...-1....0....0....0....1....1....0....1
..1....0....1....0....1....1....1....1....1....0....1....0....0....1....1

Crossrefs

Column 1 of A208805.

Sequence in context: A362641 A039792 A076358 * A090522 A114728 A057676

Adjacent sequences: A208795 A208796 A208797 * A208799 A208800 A208801

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Extensions

a(29)-a(32) from Andrew Howroyd, Mar 02 2017

Status

approved