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%I #22 Jun 02 2024 14:05:04
%S 0,2,4,8,40,116,234,258,532,1048,1062,1590,2594,3286,4036,6232,6700,
%T 7800,12002,13296,23124,29338,181306
%N Numbers k such that 6*10^k + 17 is prime.
%C For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 0 followed by the digits 17 is prime (see Example section).
%C a(24) > 2*10^5.
%C If k is odd then 6*10^k + 17 is divisible by 11. - _David Radcliffe_, Sep 04 2018
%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/prime_difficulty.txt">Search for 60w17</a>.
%e 4 is in this sequence because 6*10^4 + 17 = 60017 is prime.
%e Initial terms and associated primes:
%e a(1) = 0, 23;
%e a(2) = 2, 617;
%e a(3) = 4, 60017;
%e a(4) = 8, 600000017;
%e a(5) = 40, 60000000000000000000000000000000000000017; etc.
%t Select[Range[0, 100000], PrimeQ{6*10^# + 17] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,2
%A _Robert Price_, Apr 23 2017
%E a(23) from _Robert Price_, Apr 07 2019
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