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A071380
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Numbers n such that (26^n+1)/27 is a prime.
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15
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OFFSET
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1,1
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COMMENTS
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Some of the larger terms may only correspond to probable primes.
a(9) > 10^5. - Robert Price, Jul 07 2013
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LINKS
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Table of n, a(n) for n=1..8.
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
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MATHEMATICA
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Select[Range[3000], PrimeQ[(26^# + 1) / 27] &] (* Vincenzo Librandi, Oct 29 2017 *)
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PROG
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(PARI) isok(n) = (denominator(p=(26^n+1)/27)==1) && isprime(p); \\ Michel Marcus, Oct 29 2017
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CROSSREFS
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Cf. A057191, A071381.
Sequence in context: A080158 A156935 A308965 * A142423 A159495 A125423
Adjacent sequences: A071377 A071378 A071379 * A071381 A071382 A071383
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KEYWORD
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nonn,more
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AUTHOR
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Rick L. Shepherd, May 22 2002
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STATUS
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approved
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