OFFSET
1,1
EXAMPLE
n=87=3.29:phi[87]=56,56-phi[56]=56-24=32
MATHEMATICA
Do[s= EulerPhi[n]-EulerPhi[EulerPhi[n]]; If[IntegerQ[Log[2, s]]&&!PrimeQ[n], Print[n]], {n, 1, 10000000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, May 08 2002
STATUS
approved