A098903 Odd numbers whose number of distinct prime factors is also odd.

3, 5, 7, 9, 11, 13, 17, 19, 23, 25, 27, 29, 31, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 105, 107, 109, 113, 121, 125, 127, 131, 137, 139, 149, 151, 157, 163, 165, 167, 169, 173, 179, 181, 191, 193, 195, 197, 199, 211, 223, 227, 229

Offset: 1

Author

Shyam Sunder Gupta, Oct 14 2004

Keywords

• nonn
• easy

Comments

This will also contain all odd primes.

Examples

			25 is a member of sequence because 25 is odd and number of distinct prime factors of 25 i.e. 1 is also odd.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A001221.

Programs

Mathematica

Select[Range[300],And@@OddQ[{#,PrimeNu[#]}]&] (* Harvey P. Dale, Feb 19 2014 *)
Select[Range[1,301,2],OddQ[PrimeNu[#]]&] (* Harvey P. Dale, Feb 15 2025 *)