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Search: id:A066516
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| A066516 |
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Numbers n such that f(sigma(n)) = EulerPhi(n), where f is the prime gaps function given by f(m) = p(m+1)-p(m) and p(m) denotes the m-th prime. |
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1
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OFFSET
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1,2
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EXAMPLE
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f(sigma(4)) = f(7) = p(8)-p(7) = 19-17 = 2 = EulerPhi(4).
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MATHEMATICA
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f[x_] := Prime[x + 1] - Prime[x]; Select[Range[1, 10^5], f[DivisorSigma[1, # ]] == EulerPhi[ # ] &]
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CROSSREFS
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Sequence in context: A041857 A041034 A042535 this_sequence A047184 A002509 A100234
Adjacent sequences: A066513 A066514 A066515 this_sequence A066517 A066518 A066519
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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), Jan 04 2002
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EXTENSIONS
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No more terms below 10^6 - Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 05 2002
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