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%I #11 Jan 17 2019 13:44:08
%S 1,3,7,9,10,19,21,22,43,46,58,87,216,549,604,1147,1858,2952,3684,4057,
%T 4246,4354,8212,8289,9013,16968,19107,57754,61348,88254
%N Numbers k such that 5*10^k + 59 is prime.
%C For k>1, numbers such that the digit 5 followed by k-2 occurrences of the digit 0 followed by the digits 59 is prime (see Example section).
%C a(31) > 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 50w59.</a>
%e 3 is in this sequence because 5*10^3 + 59 = 5059 is prime.
%e Initial terms and primes associated:
%e a(1) = 1, 109;
%e a(2) = 3, 5059;
%e a(3) = 7, 50000059;
%e a(4) = 9, 5000000059;
%e a(5) = 10, 50000000059, etc.
%t Select[Range[0, 100000], PrimeQ[5*10^# + 59] &]
%o (PARI) is(n)=ispseudoprime(5*10^n + 59) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more
%O 1,2
%A _Robert Price_, Sep 05 2016
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