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Search: id:A075863
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| A075863 |
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phi(phi(n)) = sum of prime factors of n. |
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+0
1
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| 8, 45, 55, 95, 126, 132, 198, 215, 228, 516, 2855, 6852, 7655, 18372
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OFFSET
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2,1
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EXAMPLE
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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
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Select[Range[2, 10^5], EulerPhi[EulerPhi[ # ]] == Apply[Plus, Transpose[FactorInteger[ # ]][[1]]] &]
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CROSSREFS
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Sequence in context: A001689 A028565 A129553 this_sequence A118838 A100648 A128091
Adjacent sequences: A075860 A075861 A075862 this_sequence A075864 A075865 A075866
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 15 2002
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