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A046390 Squarefree odd numbers with exactly 4 distinct prime factors. 6

%I #23 Jan 07 2015 05:08:16

%S 1155,1365,1785,1995,2145,2415,2805,3003,3045,3135,3255,3315,3705,

%T 3795,3885,3927,4305,4389,4485,4515,4641,4785,4845,4935,5005,5115,

%U 5187,5313,5565,5655,5865,6045,6105,6195,6279,6405,6545,6555,6699,6765,6783,7035

%N Squarefree odd numbers with exactly 4 distinct prime factors.

%H T. D. Noe, <a href="/A046390/b046390.txt">Table of n, a(n) for n=1..1000</a>

%t f[n_]:=Last/@FactorInteger[n]=={1,1,1,1}&&FactorInteger[n][[1,1]]>2; lst={};Do[If[f[n],AppendTo[lst,n]],{n,8!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Nov 23 2009 *)

%t Select[Range[1,8001,2],PrimeNu[#]==PrimeOmega[#]==4&] (* _Harvey P. Dale_, Mar 28 2013 *)

%Y Cf. A046317, A046406.

%K nonn

%O 1,1

%A _Patrick De Geest_, Jun 15 1998

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Last modified March 28 14:21 EDT 2024. Contains 371254 sequences. (Running on oeis4.)