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%I #9 Jun 06 2019 09:51:19
%S 0,1,3,6,7,12,31,33,997,1134,3253,3462,6154,9345,10558,13251,15169,
%T 18511,19219,22476,25536,31399,35997,51793,124735
%N Numbers k such that (56*10^k + 367)/9 is prime.
%C For k>1, numbers such that the digit 6 followed by k-2 occurrences of the digit 2 followed by the digits 63 is prime (see Example section).
%C a(26) > 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 62w63</a>.
%e 3 is in this sequence because (56*10^3 + 367)/9 = 6263 is prime.
%e Initial terms and primes associated:
%e a(1) = 0, 47;
%e a(2) = 1, 103;
%e a(3) = 3, 6263;
%e a(4) = 6, 6222263;
%e a(5) = 7, 62222263; etc.
%t Select[Range[0, 100000], PrimeQ[(56*10^# + 367)/9] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,3
%A _Robert Price_, Oct 25 2017
%E a(25) from _Robert Price_, Jun 06 2019
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