A175786 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

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

MATHEMATICA

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

PROG

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

CROSSREFS