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A015706
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Odd numbers k that divide phi(k)*sigma(k).
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2
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1, 117, 135, 775, 819, 891, 1521, 1701, 2325, 3159, 3375, 4455, 5733, 6875, 6975, 10935, 11907, 19773, 20625, 20925, 22113, 22275, 24025, 40131, 41067, 43875, 44375, 49005, 61875, 62775, 68607, 72075, 75625, 83349, 84375, 85293
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Select[Range[1, 85301, 2], Divisible[EulerPhi[#]DivisorSigma[1, #], #]&] (* Harvey P. Dale, Aug 27 2013 *)
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PROG
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(PARI) isok(n) = (n%2) && !(sigma(n)*eulerphi(n) % n); \\ Michel Marcus, Oct 02 2017
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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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