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A098902 Even numbers whose number of distinct prime factors is also even. 6

%I #12 Apr 06 2018 15:32:28

%S 6,10,12,14,18,20,22,24,26,28,34,36,38,40,44,46,48,50,52,54,56,58,62,

%T 68,72,74,76,80,82,86,88,92,94,96,98,100,104,106,108,112,116,118,122,

%U 124,134,136,142,144,146,148,152,158,160,162,164,166,172,176,178,184,188

%N Even numbers whose number of distinct prime factors is also even.

%H Vincenzo Librandi, <a href="/A098902/b098902.txt">Table of n, a(n) for n = 1..1000</a>

%e a(3)=12 because 12 is even and number of distinct prime factors of 12 is also even i.e. 2

%t Select[Range[800], And@@EvenQ[{#, PrimeNu[#]}]&] (* _Vincenzo Librandi_, Feb 21 2014 *)

%t Select[Range[0,200,2],EvenQ[PrimeNu[#]]&] (* _Harvey P. Dale_, Apr 06 2018 *)

%Y Cf. A001221.

%K nonn,easy

%O 1,1

%A _Shyam Sunder Gupta_, Oct 14 2004

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