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A138066
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Least k>0 such that (2n-1)^k + 2 is prime, or 0 if no such number exists.
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1
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1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 11, 0, 1, 1, 0, 2, 1, 0, 1, 1, 0, 1, 113, 0, 1, 7, 0, 1, 1, 0, 3, 1, 0, 1, 1, 0, 12, 1, 0, 1, 3, 0, 1, 255, 0, 8, 1, 0, 1, 1, 0, 1, 1, 0, 1, 3, 0, 2, 15, 0, 2, 1, 0, 1, 23, 0, 1, 1, 0, 4, 3, 0, 1, 1, 0, 3, 1, 0, 136, 1, 0, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,12
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COMMENTS
| a(3n+1) = 0 for n>0.
a(84) > 100000. [From Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 10 2011]
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CROSSREFS
| Cf. A084713 = Smallest prime of the form (2n-1)^k + 2, or 0 if no such number exists. Cf. A138067 = Least k>1 such that (2n-1)^k + 2 is prime, or 0 if no such number exists. Cf. A051783 = Numbers n such that 3^n + 2 is prime. Cf. A087885 = Numbers n such that 5^n + 2 is prime. Cf. A090649, A109076, A113480, A138048, A138049, A138050, A138051, A087886, A113481.
Sequence in context: A113043 A110408 A179920 * A173189 A115595 A187553
Adjacent sequences: A138063 A138064 A138065 * A138067 A138068 A138069
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KEYWORD
| hard,more,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Mar 02 2008
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