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Search: id:A127996
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| A127996 |
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Numbers n such that (21^n - 1)/20 is prime. |
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+0
13
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OFFSET
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1,1
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REFERENCES
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H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.
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LINKS
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H. Lifchitz, Mersenne and Fermat primes field
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MATHEMATICA
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Select[Prime[Range[100]], PrimeQ[(21^#-1)/20]&]
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CROSSREFS
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Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035. Cf. A127995, A127997, A127998, A127999, A128000, A098438, A128002, A128003, A128004, A128005.
Sequence in context: A023865 A024592 A078116 this_sequence A032008 A061368 A145701
Adjacent sequences: A127993 A127994 A127995 this_sequence A127997 A127998 A127999
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KEYWORD
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hard,more,nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007
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