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A083685
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a(n) is the smallest prime of the form k*lcm(1..n) - 1.
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1
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2, 3, 5, 11, 59, 59, 419, 839, 5039, 5039, 55439, 55439, 1081079, 1081079, 1081079, 1441439, 24504479, 24504479, 232792559, 232792559, 232792559, 232792559, 5354228879, 5354228879, 53542288799, 53542288799, 1044074631599
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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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a(9) = 5039: lcm(1..9) = 2520; 2519 is not a prime but 2*2520 - 1 = 5039 is a prime.
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MATHEMATICA
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spf[n_]:=Module[{c=LCM@@Range[n], k=1}, While[!PrimeQ[k*c-1], k++]; k*c-1]; Array[spf, 30] (* Harvey P. Dale, Jan 15 2022 *)
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PROG
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(PARI) a(n) = {my(lcmn = lcm(vector(n, k, k)), k = 1); while(!isprime(p = k*lcmn-1), k++); p; } \\ Michel Marcus, Mar 15 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 15 2003
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EXTENSIONS
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STATUS
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approved
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