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A038779
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An intermediate sequence for nonisomorphic circulant directed p^2-graphs, indexed by odd primes p.
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1
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10, 70, 700, 104968, 1398500, 268439590, 3817763740, 799645010860, 2573485510942780, 38430716856090160, 131176846748288854980, 30223145490393217217464, 460543169377106318541400, 107646959937860684094362500, 390046338531762979375904093800
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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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a(p^2) = (1/(p-1)) * Sum_{r|p-1} phi(r) * 2^(2*(p-1)/r). - Sean A. Irvine, Feb 14 2021
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PROG
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(PARI) a(n) = my(p=prime(n+1)); (1/(p-1)) * sumdiv(p-1, r, eulerphi(r) * 2^(2*(p-1)/r)); \\ Michel Marcus, Feb 14 2021
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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