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

6, 10, 12, 14, 18, 20, 22, 24, 26, 28, 34, 36, 38, 40, 44, 46, 48, 50, 52, 54, 56, 58, 62, 68, 72, 74, 76, 80, 82, 86, 88, 92, 94, 96, 98, 100, 104, 106, 108, 112, 116, 118, 122, 124, 134, 136, 142, 144, 146, 148, 152, 158, 160, 162, 164, 166, 172, 176, 178, 184, 188

Offset: 1

Author

Shyam Sunder Gupta, Oct 14 2004

Keywords

• nonn
• easy

Examples

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

Links

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

Crossrefs

Cf. A001221.

Programs

Mathematica

Select[Range[800], And@@EvenQ[{#, PrimeNu[#]}]&] (* Vincenzo Librandi, Feb 21 2014 *)
Select[Range[0,200,2],EvenQ[PrimeNu[#]]&] (* Harvey P. Dale, Apr 06 2018 *)