A055743 Phi(n) has fewer distinct prime divisors than n.

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

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: A264964 A195064 A328926 * A354424 A189680 A189395

Adjacent sequences: A055740 A055741 A055742 * A055744 A055745 A055746

Keyword

nonn

Author

Labos Elemer, Jul 11 2000

Status

approved