A190466 - OEIS

%I #10 May 13 2013 01:49:35

%S 5760,8064,9600,12672,14976,18816,19584,21888,22400,26496,31360,33408,

%T 35200,35712,41600,42624,43740,46464,47232,49536,54144,54400,60800,

%U 61056,61236,64896,67968,68992,70272,73600,77184,77440,81536,81792

%N Numbers with prime factorization pq^2r^7.

%H T. D. Noe, <a href="/A190466/b190466.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]]=={1,2,7}; Select[Range[150000],f]

%o (PARI) list(lim)=my(v=List(),t1,t2);forprime(p=2, (lim\12)^(1/7), t1=p^7;forprime(q=2, sqrt(lim\t1), if(p==q, next);t2=t1*q^2;forprime(r=2, lim\t2, if(p==r||q==r, next);listput(v,t2*r)))); vecsort(Vec(v)) \\ _Charles R Greathouse IV_, Jul 24 2011

%Y Cf. A179747, A190465.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 10 2011