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A208670
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Number of 2n-bead necklaces labeled with numbers 1..7 allowing reversal, with neighbors differing by exactly 1.
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1
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6, 11, 20, 41, 86, 208, 514, 1398, 3934, 11576, 34850, 107303, 334396, 1053851, 3345320, 10685570, 34292064, 110498897, 357256018, 1158492478, 3766458404, 12274037845, 40082339406, 131144365904, 429838330172, 1411104048106, 4639351259122, 15273992343065
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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All solutions for n=3:
..1....5....1....5....3....4....1....6....4....1....2....2....4....5....3....4
..2....6....2....6....4....5....2....7....5....2....3....3....5....6....4....5
..1....5....3....7....3....4....1....6....6....3....4....2....6....5....5....4
..2....6....2....6....4....5....2....7....5....4....3....3....7....6....4....5
..3....5....3....7....5....6....1....6....6....3....4....2....6....7....5....4
..2....6....2....6....4....5....2....7....5....2....3....3....5....6....4....5
..
..2....2....3....3
..3....3....4....4
..2....4....3....5
..3....5....4....6
..4....4....3....5
..3....3....4....4
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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