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%I #13 Feb 20 2020 09:51:59
%S 1,3,4,16,28,45,46,67,93,130,265,321,376,717,934,1047,1420,2547,5683,
%T 8593,9445,31086,33382,43089,76021,90745
%N Numbers k such that (85*10^k - 103)/9 is prime.
%C For k > 1, numbers such that the digit 9 followed by k-2 occurrences of the digit 4 followed by the digits 33 is prime (see Example section).
%C a(27) > 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 94w33</a>.
%e 3 is in this sequence because (85*10^3 - 103)/9 = 9433 is prime.
%e Initial terms and primes associated:
%e a(1) = 1, 83;
%e a(2) = 3, 9433;
%e a(3) = 4, 94433;
%e a(4) = 16, 94444444444444433;
%e a(5) = 28, 94444444444444444444444444433; etc.
%t Select[Range[1, 100000], PrimeQ[85*10^# - 103)/9] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,2
%A _Robert Price_, Oct 06 2017
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