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Search: id:A124516
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| A124516 |
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a(n) = least k such that 2^i*k-1 is prime for 1<=i<=n. |
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+0
8
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| 2, 2, 3, 3, 45, 45, 561330, 9549960, 42932385, 13044904290
(list; graph; listen)
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OFFSET
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1,1
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MATHEMATICA
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k = 1; Do[If[n < 5, inc = 1, inc = 15]; If[Mod[k, inc] > 0, k = k + inc - Mod[k, inc]]; While[Nand @@ PrimeQ[Table[2^j, {j, n}]*k - 1], k += inc]; Print[k], {n, 1, 10}] (*Chandler*)
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CROSSREFS
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Cf. A006254, A124485, A124493, A124494, A124017, A125113, A124514, A124515.
Cf. A071576, A101994, A101320.
Sequence in context: A097365 A156906 A053094 this_sequence A091048 A071478 A071477
Adjacent sequences: A124513 A124514 A124515 this_sequence A124517 A124518 A124519
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Nov 04 2006
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EXTENSIONS
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Definition corrected and a(10) calculated by Farideh Firoozbakht, Nov 24 2006
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