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A128461
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Numbers n such that 21^n - 2 is a prime.
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12
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1, 2, 4, 10, 21, 25, 27, 32, 60, 88, 106, 120, 146, 264, 828, 965
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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MATHEMATICA
| Do[ f = 21^n - 2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n, 1, 1000} ]
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CROSSREFS
| Cf. A084714 = smallest prime of the form (2n-1)^k - 2, or 0 if no such number exists. Cf. A128472 = smallest prime of the form (2n-1)^k - 2 for k>(2n-1), or 0 if no such number exists. Cf. A014224, A109080, A090669, A128455, A128457, A128458, A128459, A128460.
Sequence in context: A104432 A129211 A175204 * A011956 A018003 A204804
Adjacent sequences: A128458 A128459 A128460 * A128462 A128463 A128464
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KEYWORD
| hard,more,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Mar 14 2007
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EXTENSIONS
| 2 more terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 05 2007
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