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A128002
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Numbers n such that (31^n - 1)/30 is prime.
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13
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OFFSET
| 1,1
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COMMENTS
| 9973 is a term found by Richard Fischer in 2004. - Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007
No other terms < 101833 - Robert Price, Nov 26 2011
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REFERENCES
| H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.
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LINKS
| H. Lifchitz, Mersenne and Fermat primes field
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MATHEMATICA
| Select[Prime[Range[100]], PrimeQ[(31^#-1)/30]&]
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CROSSREFS
| Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035. Cf. A127995, A127996, A127997, A127998, A127999, A128000, A098438, A128003, A128004, A128005.
Sequence in context: A178491 A144861 A066436 * A074275 A051411 A195016
Adjacent sequences: A127999 A128000 A128001 * A128003 A128004 A128005
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KEYWORD
| hard,more,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(6) = 101111 by Robert Price (pamandbobprice(AT)yahoo.com), Nov 26 2011
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