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A209478
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Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.
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0
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1, 2, 1, 4, 4, 11, 15, 43, 77, 199, 423, 1080, 2514, 6355, 15529, 39429, 98875, 252551, 643133, 1653677, 4254070, 11005241, 28518931, 74179434, 193328017, 505236093, 1322919905, 3471492272, 9125743338
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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
.-1....0...-1...-1...-1....0...-1...-1....0....0....0....0...-1...-1...-1...-1
..1....0....0....0....1....0....1....1...-1...-1...-1....0...-1....0....0....0
.-1...-1....0....0...-1...-1...-1...-1....1....1....1....1....1....0....0....0
..0....0....0....1....1....0....0....0...-1...-1....0...-1...-1....1....0....0
..0....0....0....1...-1....0....0....0....0....1....0....0....1....0....0....0
..0....0....0...-1....1....1...-1....0....0...-1...-1....0....1....0....1....1
..0....0....1...-1...-1....0....1....1....1....1....1....1....0...-1...-1....1
..1....1....0....1....1....0....1....0....0....0....0....0....0....1....1....0
..1....1....1....1....1....1....1....1....1....1....1....0....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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