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%I #15 Feb 21 2024 01:48:17
%S 1680,2640,3120,3696,4080,4368,4560,5520,5670,5712,6160,6384,6864,
%T 6960,7280,7440,7728,8880,8910,8976,9520,9744,9840,10032,10320,10416,
%U 10530,10608,10640,11280,11440,11856,12144,12432,12474,12720,12880,13770
%N Numbers of the form p^4*q*r*s where p, q, r, and s are distinct primes.
%H T. D. Noe, <a href="/A179693/b179693.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]]=={1,1,1,4}; Select[Range[15000], f]
%t Take[Union[First[#]^4 Times@@Rest[#]&/@Flatten[ Permutations/@ Subsets[ Prime[Range[20]],{4}],1]],50] (* _Harvey P. Dale_, Jan 26 2013 *)
%o (PARI) list(lim)=my(v=List(),t1,t2,t3); forprime(p=2,sqrtnint(lim\30, 4), t1=p^4; 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
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Jul 24 2010
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