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A047630
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Numbers n such that n | Sigma(n) * Phi(n) and n not congruent to 0 (mod 6).
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0
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1, 28, 40, 117, 135, 196, 200, 224, 496, 640, 775, 819, 891, 1000, 1372, 1521, 1550, 1568, 1701, 1792, 2176, 2325, 2480, 3100, 3159, 3200, 3375, 3724, 4455, 5000, 5632, 5733, 6200, 6860, 6875, 6975, 8128, 9604, 10240, 10880, 10935, 10976, 11907
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| George E. Andrews, "Number Theory," Dover Books, NY, 1971, Page 84.
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MATHEMATICA
| Do[ If[ Mod[ n, 6 ]!=0, If[ Mod[ DivisorSigma[ 1, n ]*EulerPhi[ n ], n ]==0, Print[ n ] ] ], {n, 1, 25000} ]
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CROSSREFS
| Cf. A011775.
Sequence in context: A109798 A084807 A184032 * A135789 A154035 A025368
Adjacent sequences: A047627 A047628 A047629 * A047631 A047632 A047633
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KEYWORD
| easy,nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 22 2000
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