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A057191 Numbers n such that (25^n+1)/26 is a prime. 15
3, 7, 23, 29, 59, 1249, 1709, 1823, 1931, 3433, 8863, 43201, 78707 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

a(14) > 10^5. - Robert Price, Jun 10 2013

LINKS

Table of n, a(n) for n=1..13.

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[0, 2000], PrimeQ[(25^# + 1) / 26] &] (* Vincenzo Librandi, Oct 29 2017 *)

PROG

(PARI) isok(n) = (denominator(p=(25^n+1)/26)==1) && isprime(p); \\ Michel Marcus, Oct 29 2017

CROSSREFS

Sequence in context: A262250 A139513 A144593 * A090548 A087309 A127781

Adjacent sequences:  A057188 A057189 A057190 * A057192 A057193 A057194

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Sep 15 2000

EXTENSIONS

a(12)-a(13) from Robert Price, Jun 10 2013

STATUS

approved

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Last modified December 5 22:37 EST 2019. Contains 329782 sequences. (Running on oeis4.)