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%I #32 Jul 19 2023 07:45:13
%S 510510,570570,690690,746130,870870,881790,903210,930930,1009470,
%T 1021020,1067430,1111110,1138830,1141140,1193010,1217370,1231230,
%U 1272810,1291290,1345890,1360590,1381380,1385670,1411410,1438710
%N Numbers that are divisible by exactly 7 distinct primes.
%H Amiram Eldar, <a href="/A176655/b176655.txt">Table of n, a(n) for n = 1..10000</a>
%e 1711710 = 2 * 3^2 * 5 * 7 * 11 * 13 * 19.
%t Select[Range[9!,5*9! ],Length[FactorInteger[ # ]]==7&]
%t Select[Range[144*10^4],PrimeNu[#]==7&] (* _Harvey P. Dale_, Jul 05 2022 *)
%o (PARI) isA176655(n)=omega(n)==7 \\ _Charles R Greathouse IV_, Mar 11 2011
%o (PARI) (PARI) A246655(lim)=my(v=List(primes([2,lim\=1]))); for(e=2,logint(lim,2), forprime(p=2,sqrtnint(lim,e), listput(v,p^e))); Set(v)
%o list(lim,pr=7)=if(pr==1, return(A246655(lim))); my(v=List(),pr1=pr-1,mx=prod(i=1,pr1,prime(i))); forprime(p=prime(pr),lim\mx, my(u=list(lim\p,pr1)); for(i=1,#u,listput(v,p*u[i]))); Set(v) \\ _Charles R Greathouse IV_, Feb 03 2023
%Y Row 7 of A125666.
%Y Cf. A046386, A046387, A067885, A123321.
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Apr 22 2010
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