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%I #27 May 12 2020 08:53:13
%S 9,15,18,21,25,27,30,33,35,36,39,42,45,49,50,51,54,55,57,60,63,65,66,
%T 69,70,72,75,77,78,81,84,85,87,90,91,93,95,98,99,100,102,105,108,110,
%U 111,114,115,117,119,120,121,123,125,126,129,130,132,133,135,138,140,141
%N Numbers with at least two odd prime factors (not necessarily distinct).
%C Also polite numbers (A138591) that can be expressed as the sum of two or more consecutive integers in more than one ways. For example 9=4+5 and 9=2+3+4. Also 15=7+8, 15=4+5+6 and 15=1+2+3+4+5. - _Jayanta Basu_, Apr 30 2013
%H Charles R Greathouse IV, <a href="/A105441/b105441.txt">Table of n, a(n) for n = 1..10000</a>
%F A087436(a(n)) > 1.
%F A001227(a(n)) > 2. [_Reinhard Zumkeller_, May 01 2012]
%t opf3Q[n_]:=Count[Flatten[Table[First[#],{Last[#]}]&/@FactorInteger[n]], _?OddQ]>1 (* _Harvey P. Dale_, Jun 13 2011 *)
%o (PARI) upTo(lim)=my(v=List(),p=7,m);forprime(q=8,lim,forstep(n=p+2,q-2,2,m=n;while(m<=lim,listput(v,m);m<<=1));p=q);forstep(n=p+2,lim,2,listput(v,n));vecsort(Vec(v)) \\ _Charles R Greathouse IV_, Aug 08 2011
%o (PARI) is(n)=n>>=valuation(n,2); !isprime(n) && n>1 \\ _Charles R Greathouse IV_, Apr 30 2013
%o (Haskell)
%o a105441 n = a105441_list !! (n-1)
%o a105441_list = filter ((> 2) . a001227) [1..]
%o -- _Reinhard Zumkeller_, May 01 2012
%Y Complement of A093641; A093642 is a subsequence.
%Y Cf. A001227, A087436, A138591.
%K nonn,easy
%O 1,1
%A _Reinhard Zumkeller_, Apr 09 2005
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