cp's OEIS Frontend

A190381 Numbers with prime factorization pqrstuv^2.

%I A190381 #11 May 20 2017 11:45:17
%S A190381 1021020,1141140,1381380,1492260,1531530,1711710,1741740,1763580,
%T A190381 1806420,1861860,2018940,2072070,2134860,2222220,2238390,2277660,
%U A190381 2386020,2434740,2462460,2545620,2552550,2582580,2612610,2645370,2691780,2709630
%N A190381 Numbers with prime factorization pqrstuv^2.
%H A190381 T. D. Noe, <a href="/A190381/b190381.txt">Table of n, a(n) for n = 1..1000</a>
%H A190381 Will Nicholes, <a href="http://willnicholes.com/math/primesiglist.htm">Prime Signatures</a>
%H A190381 <a href="/index/Pri#prime_signature">Index to sequences related to prime signature</a>
%t A190381 f[n_]:=Sort[Last/@FactorInteger[n]]=={1,1,1,1,1,1,2};Select[Range[3000000],f]
%o A190381 (PARI) list(lim)=my(v=List(),t1,t2,t3,t4,t5,t6); forprime(p1=2,sqrtint(lim\30030), t1=p1^2; forprime(p2=2,lim\(2310*t1), if(p2==p1, next); t2=p2*t1; forprime(p3=2,lim\(210*t2), if(p3==p1 || p3==p2, next); t3=p3*t2; forprime(p4=2,lim\(30*t3), if(p4==p1 || p4==p2 || p4==p3, next); t4=p4*t3; forprime(p5=2,lim\(6*t4), if(p5==p1 || p5==p2 || p5==p3 || p5==p4, next); t5=p5*t4; forprime(p6=2,lim\(2*t5), if(p6==p1 || p6==p2 || p6==p3 || p6==p4 || p6==p5, next); t6=p6*t5; forprime(p7=2,lim\t6, if(p7==p1 || p7==p2 || p7==p3 || p7==p4 || p7==p5 || p7==p6, next); listput(v, t6*p7)))))))); Set(v) \\ _Charles R Greathouse IV_, Aug 25 2016
%Y A190381 Cf. A190378, A190380.
%K A190381 nonn
%O A190381 1,1
%A A190381 _Vladimir Joseph Stephan Orlovsky_, May 09 2011