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A098903 Odd numbers whose number of distinct prime factors is also odd. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 21 18:05 EDT 2020. Contains 337919 sequences. (Running on oeis4.)