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A066465
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Numbers n such that sigma(phi(sigma(n))) = phi(n).
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1
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1, 13, 43, 97, 211, 533, 1133, 2627, 3907, 4687, 4801, 11231, 15689, 33613, 45995, 82643, 92543, 106571, 143903, 156383, 159947, 173239, 190399, 370913, 390247, 393049, 437747, 487547, 513193, 519601, 577633, 616399, 715163, 740213, 883387
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Select[Range[1, 10^6], DivisorSigma[1, EulerPhi[DivisorSigma[1, # ]]] == EulerPhi[ # ] &]
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PROG
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(PARI) { n=0; for (m=1, 10^10, if (sigma(eulerphi(sigma(m))) == eulerphi(m), write("b066465.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 17 2010
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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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