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A067384
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Numbers n such that sigma(phi(n))/sigma(n) = 4.
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6
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121679, 1043909, 2350171, 2918263, 3396103, 3566807, 3688067, 4019467, 4562827, 5963407, 7300697, 7485979, 7853933, 8103301, 8364151, 9237779, 9514213, 9638527, 10531123, 11094619, 11384447, 12721937, 13576267
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Subset of A066881. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 30 2008]
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LINKS
| Donovan Johnson, Table of n, a(n) for n = 1..500
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MATHEMATICA
| For[ n=1, True, n++, If[ DivisorSigma[ 1, EulerPhi[ n ] ]/DivisorSigma[ 1, n ]==4, Print[ n ] ] ]
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CROSSREFS
| Cf. A033631, A066831, A067382, A067383, A067385, A197952.
Sequence in context: A061128 A068136 A135495 * A066881 A048903 A185864
Adjacent sequences: A067381 A067382 A067383 * A067385 A067386 A067387
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KEYWORD
| nonn
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AUTHOR
| Dean Hickerson (dean.hickerson(AT)yahoo.com), Jan 20 2002
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