This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A190471 #14 Mar 07 2024 01:27:08
%S A190471 32400,63504,90000,156816,202500,219024,345744,374544,467856,490000,
%T A190471 685584,777924,960400,1089936,1210000,1245456,1690000,1774224,2108304,
%U A190471 2178576,2396304,2480625,2862864,2890000,3610000,3640464,4112784,4511376
%N A190471 Numbers with prime factorization p^2*q^4*r^4 where p, q, and r are distinct primes.
%H A190471 T. D. Noe, <a href="/A190471/b190471.txt">Table of n, a(n) for n = 1..1000</a>
%H A190471 Will Nicholes, <a href="https://willnicholes.com/2010/06/06/list-of-prime-signatures">List of prime signatures</a>, 2010.
%H A190471 <a href="/index/Pri#prime_signature">Index to sequences related to prime signature</a>.
%F A190471 Sum_{n>=1} 1/a(n) = P(2)*P(4)^2/2 - P(2)*P(8)/2 - P(4)*P(6) + P(10) = 0.00010139253539568059065..., where P is the prime zeta function. - _Amiram Eldar_, Mar 07 2024
%t A190471 f[n_]:=Sort[Last/@FactorInteger[n]]=={2,4,4}; Select[Range[3500000],f] (*and*) lst={}; Do[If[k!=n && k!=m && n!=m, AppendTo[lst, Prime[k]^2*Prime[n]^4*Prime[m]^4]], {n,33}, {m,33}, {k,33}]; Take[Union@lst,60]
%o A190471 (PARI) list(lim)=my(v=List(),t1,t2);forprime(p=2, (lim\4)^(1/8), t1=p^4;forprime(q=p+1, (lim\t1)^(1/4), t2=t1*q^4;forprime(r=2, sqrt(lim\t2), if(p==r||q==r, next);listput(v,t2*r^2)))); Set(v) \\ _Charles R Greathouse IV_, Aug 25 2016
%Y A190471 Cf. A190469, A190470.
%Y A190471 Cf. A085548, A085964, A085966, A085968.
%K A190471 nonn
%O A190471 1,1
%A A190471 _Vladimir Joseph Stephan Orlovsky_, May 10 2011