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%I #16 Jan 17 2019 13:44:09
%S 1,2,4,7,18,19,22,26,36,46,49,64,82,121,1204,1716,2359,4541,7194,8095,
%T 14857,18596,27648,37066,109861,171391
%N Numbers k such that 3*10^k + 59 is prime.
%C For k > 1, numbers such that the digit 3 followed by k-2 occurrences of the digit 0 followed by the digits 59 is prime (see Example section).
%C a(27) > 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 30w59.</a>
%e 4 is in this sequence because 3*10^4 + 59 = 30059 is prime.
%e Initial terms and primes associated:
%e a(1) = 1, 89;
%e a(2) = 2, 359;
%e a(3) = 4, 30059;
%e a(4) = 7; 30000059;
%e a(5) = 18, 3000000000000000059; etc.
%t Select[Range[0, 100000], PrimeQ[3*10^# + 59] &]
%o (PARI) isok(k) = ispseudoprime(3*10^k + 59) \\ _Altug Alkan_, Aug 13 2017
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,2
%A _Robert Price_, Aug 13 2017
%E a(25)-a(26) from _Robert Price_, Aug 25 2018
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