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
Keywords
Examples
phi(41) + 41 = 81 = 3^4.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..500
Programs
-
Mathematica
Select[Range[140000],IntegerQ[Surd[#+EulerPhi[#],4]]&] (* Harvey P. Dale, Sep 27 2020 *)
-
PARI
isok(n) = ispower(eulerphi(n) + n, 4); \\ Michel Marcus, Jan 09 2014