A049198 Numbers that are not squarefree whose Euler totient function is squarefree.

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

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) isok(k)=!issquarefree(k) && issquarefree(eulerphi(k)) \\ Donovan Johnson, Jun 20 2012

Crossrefs

Intersection of A049149 and A013929.

Cf. A000010, A005117, A049199.

Sequence in context: A261983 A074896 A015713 * A146303 A344999 A203205

Adjacent sequences: A049195 A049196 A049197 * A049199 A049200 A049201

Keyword

nonn,easy

Author

Labos Elemer

Status

approved