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A098904 Even numbers whose number of distinct prime factors is odd. 1
2, 4, 8, 16, 30, 32, 42, 60, 64, 66, 70, 78, 84, 90, 102, 110, 114, 120, 126, 128, 130, 132, 138, 140, 150, 154, 156, 168, 170, 174, 180, 182, 186, 190, 198, 204, 220, 222, 228, 230, 234, 238, 240, 246, 252, 256, 258, 260, 264, 266, 270, 276, 280, 282, 286, 290 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

EXAMPLE

30 is a member of sequence because 30 is even and number of distinct prime factors of 30 i.e. 3 is odd.

MATHEMATICA

Select[Select[Range[500], OddQ[PrimeNu[#]] &], EvenQ] (* G. C. Greubel, May 21 2017 *)

Select[2*Range[150], OddQ[PrimeNu[#]]&] (* Harvey P. Dale, Aug 15 2020 *)

CROSSREFS

Cf. A001221, A098902, A098903, A098905.

Sequence in context: A292793 A332835 A018469 * A248846 A046127 A271480

Adjacent sequences:  A098901 A098902 A098903 * A098905 A098906 A098907

KEYWORD

easy,nonn

AUTHOR

Shyam Sunder Gupta, Oct 14 2004

STATUS

approved

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Last modified October 26 06:11 EDT 2020. Contains 338027 sequences. (Running on oeis4.)