A190292 - OEIS

%I #9 Aug 25 2016 23:05:03

%S 6720,10560,12480,14784,16320,17472,18240,22080,22848,24640,25536,

%T 27456,27840,29120,29760,30912,35520,35904,38080,38976,39360,40128,

%U 41280,41664,42432,42560,45120,45760,47424,48576,49728,50880,51030,51520

%N Numbers with prime factorization pqrs^6.

%H T. D. Noe, <a href="/A190292/b190292.txt">Table of n, a(n) for n = 1..1000</a>

%H Will Nicholes,<a href="http://willnicholes.com/math/primesiglist.htm">Prime Signatures</a>

%t f[n_]:=Sort[Last/@FactorInteger[n]]=={1,1,1,6};Select[Range[100000],f]

%o (PARI) list(lim)=my(v=List(),t1,t2,t3); forprime(p=2,sqrtnint(lim\30, 6), t1=p^6; forprime(q=2,lim\(6*t1), if(q==p, next); t2=q*t1; forprime(r=2,lim\(2*t2), if(r==p || r==q, next); t3=r*t2; forprime(s=2,lim\t3, if(s==p || s==q || s==r, next); listput(v, t3*s))))); Set(v) \\ _Charles R Greathouse IV_, Aug 25 2016

%Y Cf. A190115, A162144.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 07 2011