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A176655
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Numbers that are divisible by exactly 7 distinct primes.
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8
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510510, 570570, 690690, 746130, 870870, 881790, 903210, 930930, 1009470, 1021020, 1067430, 1111110, 1138830, 1141140, 1193010, 1217370, 1231230, 1272810, 1291290, 1345890, 1360590, 1381380, 1385670, 1411410, 1438710
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OFFSET
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1,1
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LINKS
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EXAMPLE
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1711710 = 2 * 3^2 * 5 * 7 * 11 * 13 * 19.
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MATHEMATICA
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Select[Range[9!, 5*9! ], Length[FactorInteger[ # ]]==7&]
Select[Range[144*10^4], PrimeNu[#]==7&] (* Harvey P. Dale, Jul 05 2022 *)
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PROG
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(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)
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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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