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A047630
Numbers k that divide sigma(k) * phi(k) and are not divisible by 6.
0
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
OFFSET
1,2
REFERENCES
George E. Andrews, "Number Theory," Dover Books, NY, 1971, Page 84.
MATHEMATICA
Do[ If[ Mod[ n, 6 ]!=0, If[ Mod[ DivisorSigma[ 1, n ]*EulerPhi[ n ], n ]==0, Print[ n ] ] ], {n, 1, 25000} ]
CROSSREFS
Cf. A011775.
Sequence in context: A367975 A184032 A361855 * A135789 A219882 A154035
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Jul 22 2000
STATUS
approved