OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..5000
EXAMPLE
a(27) = 13778 = 2*83*83 is divisible by a square, but phi(13778) = 6806 = 2*41*83 is squarefree.
MATHEMATICA
Abs[ MoebiusMu[ EulerPhi[ x ] ] ]=1 and Abs[ MoebiusMu[ x ] ]=0
PROG
(PARI) for(n=4, 10^7, if(issquarefree(n)==0 & issquarefree(eulerphi(n)), print1(n ", "))) /* Donovan Johnson, Jun 20 2012 */
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved