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A075863
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phi(phi(n)) = sum of prime factors of n.
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0
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8, 45, 55, 95, 126, 132, 198, 215, 228, 516, 2855, 6852, 7655, 18372
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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EXAMPLE
| phi(phi(126)) = phi(36) = 12 and the sum of the prime factors of 126 = 2 * 3^2 * 7 is 2 + 3 + 7 = 12. Hence 126 belongs to the sequence.
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MATHEMATICA
| Select[Range[2, 10^5], EulerPhi[EulerPhi[ # ]] == Apply[Plus, Transpose[FactorInteger[ # ]][[1]]] &]
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CROSSREFS
| Sequence in context: A129553 A174643 A181268 * A118838 A153828 A100648
Adjacent sequences: A075860 A075861 A075862 * A075864 A075865 A075866
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KEYWORD
| nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 15 2002
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