A091979 Number of odd proper distinct prime divisors of n. That is, the number of odd distinct prime divisors of n that are less than n.

0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 2, 0, 0, 1, 0, 1, 2, 1, 0, 1, 1, 1, 1, 1, 0, 2, 0, 0, 2, 1, 2, 1, 0, 1, 2, 1, 0, 2, 0, 1, 2, 1, 0, 1, 1, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 2, 0, 1, 2, 0, 2, 2, 0, 1, 2, 2, 0, 1, 0, 1, 2, 1, 2, 2, 0, 1, 1, 1, 0, 2, 2, 1, 2, 1, 0, 2, 2, 1, 2, 1, 2, 1, 0, 1, 2, 1

Offset

1,15

Links

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

Example

The odd distinct prime divisors of 15 that are less than 15 are 3 and 5. Thus the number of odd distinct prime divisors of 15 that are less than 15 is 2.

Mathematica

Join[{0, 0}, Table[PrimeNu[n]-If[Divisible[n, 2], 1, 0]-If[PrimeQ[n], 1, 0], {n, 3, 100}]] (* Harvey P. Dale, Feb 08 2013 *)

Prog

(PARI) a(n)=omega(n)-if(n%2, isprime(n), 1) \\ Charles R Greathouse IV, Apr 25 2012

Crossrefs

Cf. A001227.

Sequence in context: A338203 A324930 A179519 * A321742 A228716 A029430

Adjacent sequences: A091976 A091977 A091978 * A091980 A091981 A091982

Keyword

nonn

Author

Mohammad K. Azarian, Mar 15 2004

Status

approved