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Search: id:A075865
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| A075865 |
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phi(n) = sigma(sum of prime factors of n). |
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+0
1
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| 18, 20, 52, 57, 70, 381, 426, 543, 1252, 3027, 4098, 4612, 6807
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OFFSET
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2,1
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EXAMPLE
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phi(52) = 24; sigma(sum of prime factors of 52) = sigma(15) = 24. Hence 52 belongs to the sequence.
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MATHEMATICA
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Select[Range[2, 10^5], DivisorSigma[1, Apply[Plus, Transpose[FactorInteger[ # ]][[1]]]] == EulerPhi[ # ] &]
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CROSSREFS
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Sequence in context: A064271 A113541 A113542 this_sequence A066240 A115747 A001101
Adjacent sequences: A075862 A075863 A075864 this_sequence A075866 A075867 A075868
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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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