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A098570
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Least k such that Mersenne-prime(n)*prime(k)# - 1 is prime, where prime(k)# is the k-th primorial.
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1
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1, 1, 1, 2, 1, 3, 1, 10, 9, 7, 9, 7, 36, 105, 375, 120, 280, 226, 1215, 263, 2098, 310, 2330
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OFFSET
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1,4
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LINKS
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MATHEMATICA
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f[p_] := Module[{m = 1, k = 2, q = 2}, While[!PrimeQ[k*p - 1], q = NextPrime[q]; k *= q; m++]; m]; f /@ (2^MersennePrimeExponent[Range[15]] - 1) (* Amiram Eldar, Jul 25 2021 *)
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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