login
A049198
Squarefull numbers whose Euler totient function is squarefree.
4
4, 9, 18, 49, 98, 121, 242, 529, 961, 1058, 1849, 1922, 2209, 3481, 3698, 4418, 4489, 5041, 6241, 6889, 6962, 8978, 10082, 10609, 11449, 12482, 13778, 17161, 19321, 21218, 22898, 27889, 32041, 34322, 36481, 38642, 44521, 49729, 51529, 55778
OFFSET
1,1
LINKS
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