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A190380 Numbers with prime factorization pqrst^2u^2. 2


%S 180180,235620,263340,278460,300300,311220,318780,376740,392700,

%T 401940,406980,420420,429660,437580,438900,450450,464100,475020,

%U 489060,492660,507780,512820,518700,531300,549780,550620,568260,589050,592020,595980

%N Numbers with prime factorization pqrst^2u^2.

%H T. D. Noe, <a href="/A190380/b190380.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>

%H <a href="/index/Pri#prime_signature">Index to sequences related to prime signature</a>

%t f[n_]:=Sort[Last/@FactorInteger[n]]=={1,1,1,1,2,2};Select[Range[1000000],f]

%o (PARI) list(lim)=my(v=List(),t1,t2,t3,t4,t5); forprime(p=2,sqrtint(lim\4620), t1=p^2; forprime(q=2,sqrtint(lim\(210*t1)), if(q==p, next); t2=q^2*t1; forprime(r=2,lim\(30*t2), if(r==p || r==q, next); t3=r*t2; forprime(s=2,lim\(6*t3), if(s==p || s==q || s==r, next); t4=s*t3; forprime(t=2,lim\(2*t4), if(t==p || t==q || t==r || t==s, next); t5=t*t4; forprime(u=2,lim\t5, if(u==p || u==q || u==r || u==s || u==t, next); listput(v, t5*u))))))); Set(v) \\ _Charles R Greathouse IV_, Aug 25 2016

%Y Cf. A190378, A190379.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 09 2011

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Last modified October 19 13:26 EDT 2021. Contains 348088 sequences. (Running on oeis4.)