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A209337
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Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero with no three beads in a row equal.
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0
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1, 2, 1, 4, 5, 14, 21, 51, 102, 249, 555, 1358, 3201, 7890, 19232, 47869, 118955, 298875, 752039, 1904621, 4835666, 12330144, 31521037, 80836979, 207803455, 535535393, 1383064966, 3579351724, 9280561947
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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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Some solutions for n=10:
.-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1...-1
..0....0...-1....0...-1....0....0....0....0...-1....0....0....0....0....0....0
.-1....0....0....0....0....0....0...-1...-1....0...-1....0....0...-1....1...-1
..0...-1....0....1...-1...-1...-1....0....0...-1....1...-1....1....1....0....0
..0....0...-1....0....1....0....1....1....1....1....1....0...-1...-1...-1....0
..1....1....0...-1....0....0...-1...-1...-1....1...-1....1....1....1....1....1
..1....0....1....1....1....1....1....1....1...-1....0...-1....0....0...-1....0
..0....1....0...-1....0....0....0....0...-1....1...-1....0....0....1....1....1
.-1...-1....1....1....1....0....0....0....1....0....1....1...-1...-1...-1....0
..1....1....1....0....0....1....1....1....1....1....1....1....1....1....1....0
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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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