%I
%S 2,3,5,8,9,15,20,24,41,63,66,99,281,300,462,686,726,1196,1574,2543,
%T 3023,5322,12161,13677,33797,137633
%N Numbers k such that (856*10^k  1) / 9 is prime.
%C For k>=0, numbers such that the digits 95 followed by k occurrences of the digit 1 is prime (see Example section).
%C a(27) > 2*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 951w</a>.
%e 3 is in this sequence because (856*10^3  1) / 9 = 95111 is prime.
%e Initial terms and primes associated:
%e a(1) = 2, 9511;
%e a(2) = 3, 95111;
%e a(3) = 5, 9511111;
%e a(4) = 8, 9511111111;
%e a(5) = 9, 95111111111; etc.
%t Select[Range[0, 100000], PrimeQ[(856*10^#  1) / 9] &]
%o (PARI) is(n)=ispseudoprime((856*10^n  1)/9) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard,changed
%O 1,1
%A _Robert Price_, Nov 18 2016
%E a(26) from _Robert Price_, Mar 30 2020
