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A079906
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Numbers n such that 5*6^n -1 is prime.
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9
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1, 2, 6, 7, 11, 23, 33, 48, 68, 79, 116, 151, 205, 1016, 1332, 1448, 3481, 3566, 3665, 11233, 13363, 29166, 44358, 58530
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(25) > 80000. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 26 2008]
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REFERENCES
| R. K. Guy, Unsolved Problems in Theory of Numbers, Section A3.
H. C. Williams, The primality of certain integers of the form 2Ar^n - 1, Acta Arith. 39 (1981), 7-17.
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MATHEMATICA
| Do[ If[ PrimeQ[5*6^n - 1], Print[n]], {n, 1, 5000}]
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PROG
| (PARI.2.0.17) for(n=1, 2000, if(isprime(5*6^n-1), print(n)))
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CROSSREFS
| Cf. A003307, A002235, A046865, A046866, A001771, A005541, A056725, A046867, A079907.
Sequence in context: A088227 A174000 A051678 * A189327 A172154 A072147
Adjacent sequences: A079903 A079904 A079905 * A079907 A079908 A079909
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KEYWORD
| nonn,hard
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 16 2003
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EXTENSIONS
| a(20)-a(24) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 26 2008
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