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A078167 phi[n] is a perfect 7th power. 8
1, 2, 255, 256, 272, 320, 340, 384, 408, 480, 510, 21845, 32768, 32896, 34816, 34952, 40960, 41120, 43520, 43690, 49152, 49344, 52224, 52428, 61440, 61680, 65280, 280999, 281587, 282637, 282949, 283897, 294409, 297449, 300409, 302039, 304399 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

EXAMPLE

phi of the sequence includes 1,128,16384,279936, etc..; powers arise several times; a(3)=A053576[7]=255; in sequence rather large jumps arise when power of new numbers appear.

MATHEMATICA

k=7; Do[s=EulerPhi[n]^(1/k); If[IntegerQ[s], Print[n]], {n, 1, 1000000}]

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: A034313 A177320 A070782 * A004875 A067480 A062077

Adjacent sequences:  A078164 A078165 A078166 * A078168 A078169 A078170

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Nov 27 2002

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Last modified February 16 15:58 EST 2012. Contains 205937 sequences.