A067019 Odd numbers with an odd number of prime factors (counted with multiplicity).

3, 5, 7, 11, 13, 17, 19, 23, 27, 29, 31, 37, 41, 43, 45, 47, 53, 59, 61, 63, 67, 71, 73, 75, 79, 83, 89, 97, 99, 101, 103, 105, 107, 109, 113, 117, 125, 127, 131, 137, 139, 147, 149, 151, 153, 157, 163, 165, 167, 171, 173, 175, 179, 181, 191, 193, 195, 197, 199

Offset: 1

Author

Shyam Sunder Gupta, Feb 16 2002

Keywords

• nonn

Comments

Subsequence of odd terms of A026424. - Michel Marcus, Jul 04 2015

The sequence a(1)=0, for n>1 a(n) is smallest number such that for all s,t,mAnders Hellström, Jul 08 2015

Examples

			a(9) = 27, which is odd with an odd number of prime factors, i.e., 3.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Crossrefs

Intersection of A005408 and A026424.

Setwise difference A005408 \ A046337.

Cf. A353558 (characteristic function).

Positions of the terms of the form 4u+2 (A016825) in A358669 (and in A358765).

Programs

Mathematica

Select[Range[1,301,2],OddQ[PrimeOmega[#]]&] (* Harvey P. Dale, Feb 15 2025 *)

PARI

isok(k) = { k%2 == 1 && bigomega(k)%2 == 1 } \\ Harry J. Smith, Apr 25 2010