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A055743 Phi(n) has fewer distinct prime divisors than n. 2
2, 6, 10, 12, 15, 20, 24, 30, 34, 40, 42, 48, 51, 60, 66, 68, 70, 78, 80, 84, 85, 90, 96, 102, 105, 110, 114, 120, 126, 130, 132, 136, 138, 140, 150, 156, 160, 165, 168, 170, 174, 180, 182, 190, 192, 195, 204, 210, 220, 222, 228, 230, 234, 238, 240, 246, 252 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

EXAMPLE

n=996 has 3 distinct prime divisors, 2, 3, and 83, while phi(996) = 328 = 2*2*2*41 has only 2 distinct prime factors.

MATHEMATICA

Select[Range[100], PrimeNu[EulerPhi[#]] < PrimeNu[#] &] (* G. C. Greubel, May 13 2017 *)

PROG

(PARI) is(n)=my(f=factor(n)); omega(eulerphi(f)) < #f~ \\ Charles R Greathouse IV, Mar 04 2017

CROSSREFS

Cf. A001221, A000010, A055741, A055742.

Sequence in context: A097381 A264964 A195064 * A189680 A189395 A190003

Adjacent sequences:  A055740 A055741 A055742 * A055744 A055745 A055746

KEYWORD

nonn

AUTHOR

Labos Elemer, Jul 11 2000

STATUS

approved

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Last modified October 22 15:57 EDT 2019. Contains 328318 sequences. (Running on oeis4.)