login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A057191 Numbers n such that (25^n+1)/26 is a prime. 18

%I #15 Oct 30 2017 03:52:07

%S 3,7,23,29,59,1249,1709,1823,1931,3433,8863,43201,78707

%N Numbers n such that (25^n+1)/26 is a prime.

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

%C a(14) > 10^5. - _Robert Price_, Jun 10 2013

%H H. Dubner and T. Granlund, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL3/DUBNER/dubner.html">Primes of the Form (b^n+1)/(b+1)</a>, J. Integer Sequences, 3 (2000), #P00.2.7.

%t Select[Range[0, 2000], PrimeQ[(25^# + 1) / 26] &] (* _Vincenzo Librandi_, Oct 29 2017 *)

%o (PARI) isok(n) = (denominator(p=(25^n+1)/26)==1) && isprime(p); \\ _Michel Marcus_, Oct 29 2017

%K nonn,more

%O 1,1

%A _N. J. A. Sloane_, Sep 15 2000

%E a(12)-a(13) from _Robert Price_, Jun 10 2013

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 03:33 EDT 2024. Contains 370952 sequences. (Running on oeis4.)