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A098902 Even numbers whose number of distinct prime factors is also even. 5
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

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

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 *)

CROSSREFS

Cf. A001221.

Sequence in context: A176552 A176587 A174164 * A100367 A213716 A114989

Adjacent sequences:  A098899 A098900 A098901 * A098903 A098904 A098905

KEYWORD

nonn,easy

AUTHOR

Shyam Sunder Gupta, Oct 14 2004

STATUS

approved

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Last modified May 30 05:35 EDT 2020. Contains 334712 sequences. (Running on oeis4.)