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%I #9 Jan 17 2019 13:44:09
%S 2,3,4,5,6,17,53,95,156,228,261,323,363,1208,1733,1744,2207,15728,
%T 18196,50750,66261,83811,156718
%N Numbers k such that (8*10^k - 101)/3 is prime.
%C For k>1, numbers such that the digit 2 followed by k-2 occurrences of the digit 6 followed by the digits 33 is prime (see Example section).
%C a(24) > 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 26w33</a>
%e 3 is in this sequence because (8*10^3 - 101)/3 = 2633 is prime.
%e Initial terms and primes associated:
%e a(1) = 2, 233;
%e a(2) = 3, 2633;
%e a(3) = 4, 26633;
%e a(4) = 5, 266633;
%e a(5) = 6, 2666633; etc.
%t Select[Range[2, 100000], PrimeQ[(8*10^# - 101)/3] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,1
%A _Robert Price_, Oct 23 2017
%E a(23) from _Robert Price_, Aug 14 2018
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