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%I #10 Dec 13 2019 18:40:07
%S 2,3,5,8,9,18,20,26,111,141,162,236,312,383,2093,3926,3981,4935,17126,
%T 32070,64608,86802
%N Numbers k such that (89*10^k - 539)/9 is prime.
%C For k > 1, numbers such that the digit 9 followed by k-2 occurrences of the digit 8 followed by the digits 29 is prime (see Example section).
%C a(23) > 2*10^5.
%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/primedifficulty.txt">Search for 98w29</a>.
%e 2 is in this sequence because (89*10^2 - 539)/9 = 929 is prime.
%e Initial terms and primes associated:
%e a(1) = 2, 929;
%e a(2) = 3, 9829;
%e a(3) = 5, 988829;
%e a(4) = 8, 988888829;
%e a(5) = 9, 9888888829; etc.
%t Select[Range[1, 100000], PrimeQ[(89*10^# - 539)/9] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,1
%A _Robert Price_, Nov 10 2017
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