A208965 Number of n-bead necklaces labeled with numbers -3..3 allowing reversal, with sum zero and first and second differences in -3..3.

1, 1, 2, 4, 9, 29, 87, 325, 1148, 4168, 15250, 57027, 214739, 820038, 3156251, 12243837, 47772129, 187370511, 738088612, 2919087297, 11585698838, 46133010366, 184243108172, 737834327019, 2962231908667, 11920345964795, 48072060624163, 194251242877839

Offset

1,3

Links

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

Example

All solutions for n=5:
..0...-2...-1...-1...-1...-2...-1...-1...-2
..0...-1...-1....0....0...-2...-1....0...-1
..0....1....0...-1....0....1....1....0....2
..0....2....1....1....1....2....0....0....2
..0....0....1....1....0....1....1....1...-1

Crossrefs

Column 3 of A208970.

Sequence in context: A005095 A300491 A229686 * A306505 A243789 A214935

Adjacent sequences: A208962 A208963 A208964 * A208966 A208967 A208968

Keyword

nonn

Author

R. H. Hardin, Mar 03 2012

Extensions

a(19)-a(28) from Andrew Howroyd, Mar 12 2017

Status

approved