A110918 - OEIS

%I #41 May 03 2024 15:41:27

%S 1,2,3,4,11,12,15,19,136,144,732,5754,6602,23499,39583,74254,93356,

%T 94016

%N Integers n such that 10^n+91 is a prime number.

%C No additional terms < 100000.

%C See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "10091".

%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/">List of near-repdigit-related prime numbers</a>.

%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.

%e n = 4 is a member: 10^4+91 = 10000+91 = 10091, which is prime.

%t Select[Range[2000], PrimeQ[10^# + 91] &] (* _Vincenzo Librandi_, Nov 02 2014 *)

%o (Magma) [n: n in [1..400]| IsPrime(10^n+91)]; // _Vincenzo Librandi_, Nov 02 2014

%Y Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054.

%K more,nonn

%O 1,2

%A Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

%E a(1)=1 added by _Vladimir Joseph Stephan Orlovsky_, May 02 2008

%E a(12)-a(15) from _Robert Price_, Dec 12 2010

%E Edited by _Ray Chandler_, Dec 23 2010

%E a(16)=74254 from _Robert Price_, Mar 03 2011

%E a(17)=92178 and a(18)=94016 from _Robert Price_, Apr 19 2011

%E a(17)=93356 corrected by _Robert Price_, Apr 19 2011

%E a(12) corrected by _Tyler Busby_, May 03 2024