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A138049
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Numbers n such that 21^n + 2 is prime.
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5
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0, 1, 2, 4, 7, 24, 40, 112, 310, 1026, 1286, 36566, 43717, 53753
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| No further terms < 100000. - Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 11 2011
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LINKS
| Henri & Renaud Lifchitz, PRP Records.
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MATHEMATICA
| Do[ f = 21^n + 2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n, 1, 310} ]
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CROSSREFS
| 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, A138050, A138051, A087886, A113481.
Sequence in context: A026080 A071795 A059501 * A099387 A036440 A103001
Adjacent sequences: A138046 A138047 A138048 * A138050 A138051 A138052
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KEYWORD
| nonn,more
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Mar 02 2008
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EXTENSIONS
| 1026 from Herman Jamke (hermanjamke(AT)fastmail.fm), May 01 2008
{1286, 36566} from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jul 31 2011
43717 from Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 01 2011
53753 from Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 02 2011
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