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A074874
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Numbers n such that phi(n + phi(n)) = sigma(n).
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2
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1, 3, 5, 11, 23, 55, 87, 123, 383, 501, 957, 1015, 3565, 3777, 5667, 6141, 9069, 11033, 13827, 27347, 35119, 44693, 55645, 91915, 137037, 156919, 180251, 233935, 261989, 269395, 294679, 315605, 335995, 361645, 380103, 389809, 410201, 428399, 443267
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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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sigma(23) = 24 = phi(23 + 22) = phi(23 + phi(23)), so 23 is a term of the sequence.
phi(87 + phi(87)) = phi(87 + 56) = 120 = sigma(87), so 87 is a member of the sequence.
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MATHEMATICA
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Select[Range[10^5], EulerPhi[ # + EulerPhi[ # ]] == DivisorSigma[1, # ] &]
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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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