OFFSET
1,1
LINKS
Hiroaki Yamanouchi, Table of n, a(n) for n = 1..272
EXAMPLE
6277+phi(6277)+phi(phi(6277)) = 14641 = 11^4, so 6277 is a term.
MATHEMATICA
fpQ[n_]:=Module[{epn=EulerPhi[n]}, IntegerQ[Power[n+epn+ EulerPhi[epn], (4)^-1]]]; Select[Range[800000], fpQ] (* Harvey P. Dale, Mar 23 2011 *)
PROG
(PARI)
for(n=1, 10^7, p = n+eulerphi(n)+eulerphi(eulerphi(n)); if(ispower(p)&&ispower(p)%4==0, print1(n, ", "))) \\ Derek Orr, Sep 19 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 13 2006
EXTENSIONS
a(34)-a(36) from Hiroaki Yamanouchi, Sep 19 2014
STATUS
approved