1,1

This will also contain all odd primes.

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

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

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

Cf. A001221.

Sequence in context: A112372 A082916 A325372 * A061345 A238266 A308838

Adjacent sequences: A098900 A098901 A098902 * A098904 A098905 A098906

nonn,easy

Shyam Sunder Gupta, Oct 14 2004

approved