login
A208818
Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero.
0
1, 2, 2, 5, 7, 18, 32, 84, 185, 486, 1192, 3179, 8261, 22290, 59788, 163181, 445699, 1228686, 3396224, 9440759, 26322371, 73680058, 206822134, 582308320, 1643573625, 4650401810, 13186590962, 37469003353
OFFSET
1,2
COMMENTS
Column 1 of A208825.
EXAMPLE
All solutions for n=3:
..0...-1
..0....0
..0....1
CROSSREFS
Sequence in context: A038750 A356434 A300439 * A221835 A074476 A224610
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 01 2012
STATUS
approved