A114072 Numbers k such that phi(k) + k is a fourth power.

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

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..500

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. A000010, 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