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A092584
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Numbers k such that sigma(phi(k)) == phi(sigma(k)) (mod k), that is, A033632(k)/k is an integer.
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8
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1, 5, 9, 157, 225, 242, 516, 729, 3872, 13932, 14406, 17672, 18225, 20124, 21780, 29262, 29616, 45996, 65025, 76832, 92778, 95916, 106092, 106308, 114630, 114930, 121872, 125652, 140130, 140625, 145794, 149124, 160986, 179562, 185100, 234876
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OFFSET
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1,2
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LINKS
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EXAMPLE
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Includes but is not identical with A033632.
Below 10^7 only a(2) = 5 and a(4) = 157 give A033632(n)/n nonzero.
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MATHEMATICA
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Select[Range[250000], Divisible[DivisorSigma[1, EulerPhi[#]] - EulerPhi[DivisorSigma[1, #]] , #] &] (* Amiram Eldar, Mar 12 2020 *)
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PROG
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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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