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%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