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A294570 Numbers k such that (58*10^k + 329)/9 is prime. 0

%I

%S 0,1,3,6,19,22,27,48,70,130,364,594,603,799,2442,3168,5059,5563,6523,

%T 12282,13498,34099,86242,122170,161691

%N Numbers k such that (58*10^k + 329)/9 is prime.

%C For k>1, numbers such that the digit 6 followed by k-2 occurrences of the digit 4 followed by the digits 81 is prime (see Example section).

%C a(26) > 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 64w81</a>.

%e 3 is in this sequence because (58*10^3 + 329)/9 = 6481 is prime.

%e Initial terms and primes associated:

%e a(1) = 0, 43;

%e a(2) = 1, 101;

%e a(3) = 3, 6481;

%e a(4) = 6, 6444481;

%e a(5) = 19, 64444444444444444481; etc.

%t Select[Range[0, 100000], PrimeQ[(58*10^# + 329)/9] &]

%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

%K nonn,more,hard

%O 1,3

%A _Robert Price_, Nov 02 2017

%E a(24)-a(25) from _Robert Price_, May 01 2019

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Last modified December 9 13:50 EST 2019. Contains 329877 sequences. (Running on oeis4.)