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A371611
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Number of 2*n-sided cycles with the property that one makes the same number of left and right turns while following its edges.
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1
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4, 36, 1240, 73240, 7171176, 1016813448, 198480110880, 50752206180576, 16460660622560680, 6595414427636900536, 3198428240666246044704, 1845848150787599809368856, 1250049326783769438348496480, 981653074459964543314138858320
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OFFSET
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2,1
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COMMENTS
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Cycles that differ by rotation or reflection are counted separately. By "n-sided cycles" we mean the cycles that can be drawn by connecting n equally spaced points on a circle (possibly self-intersecting).
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LINKS
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FORMULA
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a(n) is always divisible by 2*n, because the considered cycles cannot have rotational symmetry.
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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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