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A046339
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Composite numbers with an odd number of prime factors (counted with multiplicity).
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5
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8, 12, 18, 20, 27, 28, 30, 32, 42, 44, 45, 48, 50, 52, 63, 66, 68, 70, 72, 75, 76, 78, 80, 92, 98, 99, 102, 105, 108, 110, 112, 114, 116, 117, 120, 124, 125, 128, 130, 138, 147, 148, 153, 154, 162, 164, 165, 168, 170, 171, 172, 174, 175, 176, 180, 182, 186, 188
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(1)=8 as 8=2*2*2, that is 8 is a composite integer and having 3 (an odd number) prime factors.
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MATHEMATICA
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fQ[n_] := Block[{p = Plus @@ Last /@ FactorInteger@n}, OddQ[p] && p > 1]; Select[ Range@200, fQ[ # ] &] (* Robert G. Wilson v, Jan 04 2006 *)
Select[Range[200], CompositeQ[#]&&OddQ[PrimeOmega[#]]&] (* Harvey P. Dale, Oct 14 2019 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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