%I
%S 0,1,2,4,5,6,7,13,28,36,40,74,233,425,828,888,1970,2119,2338,2971,
%T 3030,14005,20190,29589,47034,47292,51457,64326,70259,90110
%N Numbers k such that (22*10^k + 161)/3 is prime.
%C For k>1, numbers such that the digit 7 followed by k2 occurrences of the digit 3 followed by the digits 87 is prime (see Example section).
%C a(31) > 10^5.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of nearrepdigitrelated numbers</a>.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/primedifficulty.txt">Search for 73w87.</a>
%e 4 is in this sequence because (22*10^4 + 161)/3 = 73387 is prime.
%e Initial terms and primes associated:
%e a(1) = 0, 61;
%e a(2) = 1, 127;
%e a(3) = 2, 787;
%e a(4) = 4, 73387;
%e a(5) = 5, 733387; etc.
%t Select[Range[0, 100000], PrimeQ[(22*10^# + 161)/3] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,3
%A _Robert Price_, Feb 10 2017
