A208797 Number of n-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and three times sum of squares <= n^2*(n+1).

1, 2, 5, 50, 561, 10372, 243678, 7202490, 247156839, 9762800723, 440697781180, 22158315689027, 1229209301535779, 75088178610750205, 4978494160384332078, 356259456157306682274, 27485448424107064539043, 2265348987116189301685523, 198721340483996173886242478, 18537738405130256739553691845

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Example

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

Crossrefs

Diagonal of A208805.

Sequence in context: A244014 A102011 A328151 * A004098 A356492 A208206

Adjacent sequences: A208794 A208795 A208796 * A208798 A208799 A208800

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Extensions

a(10)-a(20) from Andrew Howroyd, Mar 02 2017

Status

approved