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Search: id:A084891
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%I A084891
%S A084891 22,26,33,34,38,39,44,46,51,52,55,57,58,62,65,66,68,69,74,76,77,78,82,
%T A084891 85,86,87,88,91,92,93,94,95,99,102,104,106,110,111,114,115,116,117,118,
%U A084891 119,122,123,124,129,130,132,133,134,136,138,141,142,145,146
%N A084891 Multiples of 2, 3, 5, or 7, but not 7-smooth.
%C A084891 Intersection of A068191 with (A005843, A008585, A008587 and A008589); 
               union of (A005843, A008585, A008587 and A008589) without A002473.
%C A084891 A020639(a(n)) <= 7, A006530(a(n)) > 7.
%H A084891 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               SmoothNumber.html">Smooth Number</a>
%o A084891 Contribution from Cino Hilliard (hillcino368(AT)hotmail.com), Jul 03 
               2009: (Start)
%o A084891 (PARI) mult2357(m,n) = \\ mult 2,3,5,7 not 7 smooth
%o A084891 {
%o A084891 local(x,a,j,f,ln);
%o A084891 for(x=m,n,
%o A084891 f=0;
%o A084891 if(gcd(x,210)>1,
%o A084891 a = ifactor(x);
%o A084891 for(j=1,length(a),
%o A084891 if(a[j]>7,f=1;break);
%o A084891 );
%o A084891 if(f,print1(x","));
%o A084891 );
%o A084891 );
%o A084891 }
%o A084891 ifactor(n) = \\ The vector of the prime factors of n with multiplicity.
%o A084891 {
%o A084891 local(f,j,k,flist);
%o A084891 flist=[];
%o A084891 f=Vec(factor(n));
%o A084891 for(j=1,length(f[1]),
%o A084891 for(k = 1,f[2][j],flist = concat(flist,f[1][j])
%o A084891 );
%o A084891 );
%o A084891 return(flist)
%o A084891 }
%o A084891 (End)
%Y A084891 Sequence in context: A124177 A160078 A066059 this_sequence A162422 A063940 
               A046442
%Y A084891 Adjacent sequences: A084888 A084889 A084890 this_sequence A084892 A084893 
               A084894
%K A084891 nonn
%O A084891 1,1
%A A084891 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 13 2003

    
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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.


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