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%I #11 May 19 2024 21:55:29
%S 2,5,8,10,11,35,74,107,170,196,281,748,1124,2597,5189,5650,8453,10822,
%T 24554,54596,85370,140410,188999
%N Numbers k such that (44*10^k - 503)/9 is prime.
%C For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 8 followed by the digits 33 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/prime_difficulty.txt">Search for 48w33</a>.
%e 2 is in this sequence because (44*10^2 - 503)/9 = 433 is prime.
%e Initial terms and associated primes:
%e a(1) = 2, 433;
%e a(2) = 5, 488833;
%e a(3) = 8, 488888833;
%e a(4) = 10, 48888888833;
%e a(5) = 11, 488888888833; etc.
%t Select[Range[2, 100000], PrimeQ[(44*10^# - 503)/9] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,1
%A _Robert Price_, Oct 23 2017
%E a(22)-a(23) from _Robert Price_, Dec 23 2018
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