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A078166
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Numbers k such that phi(k) is a perfect sixth power.
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8
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1, 2, 85, 128, 136, 160, 170, 192, 204, 240, 4369, 8192, 8224, 8704, 8738, 10240, 10280, 10880, 12288, 12336, 13056, 15360, 15420, 16320, 47197, 47239, 47989, 49267, 49589, 50557, 51319, 52429, 52649, 55699, 57589, 57953, 59495, 63973
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OFFSET
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1,2
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COMMENTS
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LINKS
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EXAMPLE
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phi of the sequence includes 1, 64, 4096, 46656,..; powers arise several times; a(3)= A053576(6) = 85; in sequence relatively large jumps are observable when power of new numbers appear.
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MATHEMATICA
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k=6; Select[Range[65000], IntegerQ[EulerPhi[#]^(1/k)]&] (* Harvey P. Dale, Feb 20 2011 *)
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PROG
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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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