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A060172
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Number of orbits of length n under a map whose periodic points are counted by A027306.
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6
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1, 1, 1, 2, 3, 6, 9, 19, 28, 62, 93, 205, 315, 703, 1091, 2440, 3855, 8616, 13797, 30801, 49929, 111311, 182361, 405751, 671088, 1490409, 2485504, 5509504, 9256395, 20480421, 34636833, 76499520, 130150493, 286960946, 490853403, 1080476338, 1857283155, 4081876927, 7048151355
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OFFSET
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1,4
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COMMENTS
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The sequence A027306 records the number of points of period n under a map. The number of orbits of length n for this map gives the sequence above.
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LINKS
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FORMULA
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a(n) = (1/n)* Sum_{ d divides n } mu(d)*A027306(n/d).
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EXAMPLE
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u(7) = 9 since the map whose periodic points are counted by A027306 has 1 fixed point and 64 points of period 7, hence 9 orbits of length 7.
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PROG
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(PARI) a027306(n) = (2^n + if(n%2, 0, binomial(n, n/2)))/2;
a(n) = (1/n)*sumdiv(n, d, moebius(d)*a027306(n/d)); \\ Michel Marcus, Sep 11 2017
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CROSSREFS
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KEYWORD
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easy,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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