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%I #22 Jul 08 2021 05:05:54
%S 2,3,26,110,141,474,902,1746,2997,3627,3788,51162,71670,78576,104942,
%T 122592,248145
%N Numbers k such that 8*10^k + R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
%C Also numbers k such that (73*10^k - 1)/9 is prime.
%C The next term is > 10000. - _Hugo Pfoertner_, Oct 21 2004
%C a(18) > 250000. - _Robert Price_, Jan 21 2015
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/8/81111.htm#prime">Prime numbers of the form 811...11</a>.
%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>
%t Do[ If[ PrimeQ[ 8*10^n + (10^n-1)/9], Print[n]], {n, 0, 5000}]
%Y Cf. A002275, A093633.
%K hard,nonn
%O 1,1
%A _Robert G. Wilson v_, Aug 11 2000
%E a(12)-a(17) from Kamada data by _Robert Price_, Jan 21 2015
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