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A114072 Numbers k such that phi(k) + k is a fourth power. 1
12, 41, 172, 176, 192, 313, 385, 972, 1008, 1201, 2732, 2752, 2816, 3072, 6668, 7321, 14281, 15552, 16128, 25616, 29425, 41761, 43696, 43712, 44032, 45056, 49152, 78732, 78768, 79056, 81648, 84240, 97241, 106688, 123921, 139921 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

phi(41) + 41 = 81 = 3^4.

MATHEMATICA

Select[Range[140000], IntegerQ[Surd[#+EulerPhi[#], 4]]&] (* Harvey P. Dale, Sep 27 2020 *)

PROG

(PARI) isok(n) = ispower(eulerphi(n) + n, 4); \\ Michel Marcus, Jan 09 2014

CROSSREFS

Cf. A121048, subsequence of A114073.

Sequence in context: A330826 A222806 A251429 * A244793 A218712 A022672

Adjacent sequences: A114069 A114070 A114071 * A114073 A114074 A114075

KEYWORD

nonn

AUTHOR

Giovanni Resta, Feb 13 2006

STATUS

approved

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Last modified February 8 23:03 EST 2023. Contains 360153 sequences. (Running on oeis4.)