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

1,1

Comments

This will also contain all odd primes.

Links

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

Example

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

Mathematica

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

Crossrefs

Cf. A001221.

Sequence in context: A112372 A082916 A325372 * A061345 A238266 A308838

Adjacent sequences: A098900 A098901 A098902 * A098904 A098905 A098906

Keyword

nonn,easy

Author

Shyam Sunder Gupta, Oct 14 2004

Status

approved