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A108332 Integers k such that 10^k - 89 is prime. 2

%I #29 Oct 09 2023 03:15:54

%S 2,3,637,2349,29455,175093

%N Integers k such that 10^k - 89 is prime.

%C 637 corresponds to a certified prime (Primo 2.2.0 beta). - _Ryan Propper_, Nov 06 2005

%C No additional terms < 40000.

%C See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "9w11".

%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 k = 3 is a term because 10^3 - 89 = 1000 - 89 = 911, which is prime.

%t Do[If[PrimeQ[10^n - 89], Print[n]], {n, 2, 10^4}] (* _Ryan Propper_, Nov 06 2005 *)

%Y Cf. A089675, A095714, A092767.

%K nonn,more

%O 1,1

%A Julien Peter Benney (jpbenney(AT)ftml.net), Jun 30 2005

%E a(5) from _Robert Price_, Dec 15 2010

%E Edited by _Ray Chandler_, Dec 23 2010

%E a(6) from _Riley Fisher_, Oct 09 2023

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Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)