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A208820
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Number of n-bead necklaces labeled with numbers -3..3 allowing reversal, with sum zero.
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0
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1, 4, 8, 38, 155, 828, 4390, 25202, 146803, 878708, 5330524, 32785934, 203687695, 1276913732, 8065359582, 51282069040
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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LINKS
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EXAMPLE
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All solutions for n=3:
.-2....0...-2...-3...-1...-3...-1...-2
.-1....0....1....1...-1....0....0....0
..3....0....1....2....2....3....1....2
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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