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A234498
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Products p*q*r*s of distinct primes for which (p*q*r*s - 1)/2 is prime.
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4
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1155, 1995, 3135, 3255, 3315, 4935, 5115, 5187, 6783, 7035, 7095, 7215, 7395, 7455, 7755, 8463, 8547, 8715, 9867, 10335, 10455, 10695, 10815, 11055, 11715, 11739, 12243, 12903, 14595, 14835, 15855, 16107, 16359, 16779, 16863, 17043, 17255, 17355, 18183
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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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1155 = 3*5*7*11 is the least product of 4 distinct primes p,q,r,s for which (p*q*r*s-1)/2 is a prime: 577.
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MATHEMATICA
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t = Select[Range[1, 20000, 2], Map[Last, FactorInteger[#]] == Table[1, {4}] &]; Take[(t - 1)/2, 120] (* A234105 *)
v = Flatten[Position[PrimeQ[(t - 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A234498 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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