A175786 Numbers n such that the number of prime divisors of n (counted with multiplicity) is not a divisor of phi(n).

8, 12, 20, 30, 32, 44, 48, 50, 54, 64, 66, 68, 72, 75, 80, 81, 92, 96, 102, 108, 110, 112, 116, 120, 125, 128, 138, 160, 162, 164, 165, 168, 170, 174, 180, 188, 192, 208, 212, 230, 236, 240, 242, 243, 246, 252, 255, 270, 272, 275, 280, 282, 284, 288, 290, 304

Offset: 1

Author

Enrique Pérez Herrero, Sep 04 2010

Keywords

• nonn

Comments

a(n) is in the sequence if A001222(n) does not divides A000010(n).

Links

• Enrique Pérez Herrero, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A074946, A109421, A109423, A013929.

Programs

Mathematica

Select[Range[2,400],Mod[EulerPhi[#],PrimeOmega[#]]!=0&] (* Harvey P. Dale, Mar 14 2020 *)

PARI

isok(n) =  (eulerphi(n) % bigomega(n)); \\ Michel Marcus, Aug 27 2013