Search: id:A143207
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%I A143207
%S A143207 30,60,90,120,150,180,240,270,300,360,450,480,540,600,720,750,810,900,
%T A143207 960,1080,1200,1350,1440,1500,1620,1800,1920,2160,2250,2400,2430,2700,
%U A143207 2880,3000,3240,3600,3750,3840,4050,4320,4500,4800,4860
%N A143207 Numbers with exactly 3 distinct prime factors not greater than 5.
%C A143207 A001221(a(n))=3; A020639(a(n))=2; A006530(a(n))=5;
%C A143207 A143201(a(n)) = 6;
%C A143207 subsequence of A143204 and of A051037.
%C A143207 Successive k such that EulerPhi[x]/x=4/15. [From Artur Jasinski (grafix(AT)csl.pl), 
               Nov 07 2008]
%H A143207 T. D. Noe, <a href="b143207.txt">Table of n, a(n) for n=1..1000</a>
%t A143207 a = {}; Do[If[EulerPhi[x]/x == 4/15, AppendTo[a, x]], {x, 1, 11664}]; 
               a [From Artur Jasinski (grafix(AT)csl.pl), Nov 07 2008]
%Y A143207 Cf. A069819.
%Y A143207 Sequence in context: A056954 A050519 A069819 this_sequence A108454 A064783 
               A053014
%Y A143207 Adjacent sequences: A143204 A143205 A143206 this_sequence A143208 A143209 
               A143210
%K A143207 nonn
%O A143207 1,1
%A A143207 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 12 2008

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