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 A145784 Numbers with property that the number of prime factors is a multiple of 3. 5
 1, 8, 12, 18, 20, 27, 28, 30, 42, 44, 45, 50, 52, 63, 64, 66, 68, 70, 75, 76, 78, 92, 96, 98, 99, 102, 105, 110, 114, 116, 117, 124, 125, 130, 138, 144, 147, 148, 153, 154, 160, 164, 165, 170, 171, 172, 174, 175, 182, 186, 188, 190, 195, 207, 212, 216, 222 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A010872(A001222(a(n))) = 0; A014612 and A000578 are subsequences. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 MATHEMATICA Join[{1}, Select[Range[2, 230], Mod[Total[Transpose[FactorInteger[#]][[2]]], 3] == 0 &]] (* T. D. Noe, May 21 2012 *) PROG (Haskell) a145784 n = a145784_list !! (n-1) a145784_list = filter ((== 0) . a010872 . a001222) [1..] -- Reinhard Zumkeller, May 26 2012 CROSSREFS Cf. A028260. Sequence in context: A051144 A067537 A046339 * A014612 A226527 A212582 Adjacent sequences:  A145781 A145782 A145783 * A145785 A145786 A145787 KEYWORD nonn AUTHOR Reinhard Zumkeller, Oct 19 2008 STATUS approved

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Last modified August 24 03:51 EDT 2019. Contains 326260 sequences. (Running on oeis4.)