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%I #32 Sep 08 2022 08:45:15
%S 15,21,33,35,39,45,51,55,57,63,65,69,75,77,85,87,91,93,95,99,111,115,
%T 117,119,123,129,133,135,141,143,145,147,153,155,159,161,171,175,177,
%U 183,185,187,189,201,203,205,207,209,213,215,217,219,221,225,235,237
%N Odd numbers whose number of distinct prime factors is positive and even.
%H G. C. Greubel, <a href="/A098905/b098905.txt">Table of n, a(n) for n = 1..1000</a>
%e 21 is a member of sequence because 21 is odd and number of distinct prime factors of 21, i.e., 2 is even.
%t Select[Select[Range[2,400], EvenQ[PrimeNu[#]] &], OddQ] (* _G. C. Greubel_, May 09 2017 *)
%t Select[Range[3,250,2],EvenQ[PrimeNu[#]]&] (* _Harvey P. Dale_, Jan 19 2020 *)
%o (PARI) isok(n) = (n>1) && (n%2) && !(omega(n) % 2); \\ _Michel Marcus_, Jan 20 2020
%o (Magma) [k:k in [3..250 by 2]|IsEven(#PrimeDivisors(k))]; // _Marius A. Burtea_, Jan 20 2020
%Y Cf. A001221.
%K easy,nonn
%O 1,1
%A _Shyam Sunder Gupta_, Oct 14 2004
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