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A078166 Numbers n such that phi(n) is a perfect sixth power. 8
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

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.

MATHEMATICA

k=6; Select[Range[65000], IntegerQ[EulerPhi[#]^(1/k)]&]  (* Harvey P. Dale, Feb 20 2011 *)

CROSSREFS

Cf. A039770[square], A039771[cube], A078164[4th], A078165[5th], A078166[6th], A078167[7th], A078168[8th], A078169[9th], A078170[10th power], A001317, A053576, A045544, A000010.

Sequence in context: A293707 A157315 A244947 * A101578 A041881 A076542

Adjacent sequences:  A078163 A078164 A078165 * A078167 A078168 A078169

KEYWORD

nonn

AUTHOR

Labos Elemer, Nov 27 2002

STATUS

approved

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Last modified December 12 00:07 EST 2018. Contains 318052 sequences. (Running on oeis4.)