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%I #41 Mar 06 2019 15:59:39
%S 0,1,2,8,18,24,96,152,204,296,566,703,1814,4342,4626,5412,6704,6752,
%T 7096,27004,37976,173251
%N Numbers k such that (16*10^k + 107)/3 is prime.
%C For k > 1, numbers such that the digit 5 followed by k-2 occurrences of the digit 3 followed by the digits 69 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 53w69</a>
%e 2 is in this sequence because (16*10^2 + 107)/3 = 569 is prime.
%e Initial terms and primes associated:
%e a(1) = 0, 41;
%e a(2) = 1, 89;
%e a(3) = 2, 569;
%e a(4) = 8, 533333369;
%e a(5) = 18, 5333333333333333369; etc.
%t Select[Range[0, 100000], PrimeQ[(16*10^# + 107)/3] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,3
%A _Robert Price_, Nov 28 2017
%E a(22) from _Robert Price_, Mar 06 2019
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