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%I #35 May 03 2024 07:45:53
%S 1,4,7,11,14,16,22,29,36,40,65,139,149,204,842,1031,1331,1345,1505,
%T 1894,3386,3526,11092,23836,37836,138811,182614
%N Numbers k such that 3*10^k - 11 is prime.
%C Some of the larger entries may only correspond to probable primes.
%C Numbers corresponding to terms <= 842 are certified primes. - _Klaus Brockhaus_, Feb 16 2005
%C Next term > 12500. - _Ryan Propper_, Jul 21 2006
%C For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 9 followed by the digits 89 is prime. - _Robert Price_, Nov 25 2017
%C a(28) > 2*10^5. - _Robert Price_, Jul 04 2018
%H Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/prime_difficulty.txt">Search for 29w89</a>.
%t Select[Range[1,500],PrimeQ[3*10^# - 11]&] (* _Julien Kluge_, Sep 19 2016 *)
%o (PARI) is(n)=ispseudoprime(3*10^n - 11) \\ _Charles R Greathouse IV_, Jun 13 2017
%K more,nonn
%O 1,2
%A Tom Mueller (muel4503(AT)uni-trier.de), Feb 08 2005
%E a(15)-a(19) from _Klaus Brockhaus_, Feb 16 2005
%E a(20)-a(23) from _Ryan Propper_, Jul 21 2006
%E a(24)-a(25) from _Robert Price_, Nov 25 2017
%E a(26) from _Robert Price_, Jul 04 2018
%E a(27) from _Robert Price_, Jul 25 2018