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URL: https://oeis.org/A057191

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A057191
Numbers n such that (25^n+1)/26 is a prime.
18
3, 7, 23, 29, 59, 1249, 1709, 1823, 1931, 3433, 8863, 43201, 78707
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
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
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 15 2000
EXTENSIONS
a(12)-a(13) from Robert Price, Jun 10 2013
STATUS
approved