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A208821
Number of n-bead necklaces labeled with numbers -4..4 allowing reversal, with sum zero.
0
1, 5, 13, 75, 415, 2821, 19657, 144871, 1090645, 8392423, 65527045, 518173267, 4139803293, 33366946637
OFFSET
1,2
COMMENTS
Column 4 of A208825.
EXAMPLE
All solutions for n=3:
.-2...-1....0...-4...-2...-3...-3...-3...-1...-4...-2...-2...-4
.-1....0....0....1....0....0...-1....1...-1....0...-2....1....2
..3....1....0....3....2....3....4....2....2....4....4....1....2
CROSSREFS
Sequence in context: A303962 A304927 A163732 * A293259 A064169 A294208
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 01 2012
STATUS
approved