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%I #11 Feb 17 2020 10:30:01
%S 0,2,3,6,8,9,12,24,39,93,99,147,254,416,510,572,582,1488,1734,5856,
%T 19196,40112,124329
%N Numbers k such that (304*10^k - 43)/9 is prime.
%C For k>0, numbers such that the digits 33 followed by k-1 occurrences of the digit 7 followed by the digit 3 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 337w3</a>.
%e 3 is in this sequence because (304*10^3 - 43)/9 = 33773 is prime.
%e Initial terms and primes associated:
%e a(1) = 0, 29;
%e a(2) = 2, 3373;
%e a(3) = 3, 33773;
%e a(4) = 6, 33777773;
%e a(5) = 8, 3377777773; etc.
%t Select[Range[0, 100000], PrimeQ[(304*10^# - 43)/9] &]
%o (PARI) isok(k) = isprime((304*10^k - 43)/9); \\ _Michel Marcus_, Jul 16 2017
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,2
%A _Robert Price_, Jul 15 2017
%E a(23) from _Robert Price_, Feb 17 2020
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