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A071380 Numbers n such that (26^n+1)/27 is a prime. 15
11, 109, 227, 277, 347, 857, 2297, 9043 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Some of the larger terms may only correspond to probable primes.

a(9) > 10^5. - Robert Price, Jul 07 2013

LINKS

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.

MATHEMATICA

Select[Range[3000], PrimeQ[(26^# + 1) / 27] &] (* Vincenzo Librandi, Oct 29 2017 *)

PROG

(PARI) isok(n) = (denominator(p=(26^n+1)/27)==1) && isprime(p); \\ Michel Marcus, Oct 29 2017

CROSSREFS

Cf. A057191, A071381.

Sequence in context: A080158 A156935 A308965 * A142423 A159495 A125423

Adjacent sequences:  A071377 A071378 A071379 * A071381 A071382 A071383

KEYWORD

nonn,more

AUTHOR

Rick L. Shepherd, May 22 2002

STATUS

approved

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Last modified December 9 00:32 EST 2019. Contains 329871 sequences. (Running on oeis4.)