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%I #24 Jan 17 2019 13:44:07
%S 3,9,17,153,194,641,675,1461,26429,48461,72735
%N Numbers n such that 8*10^n + R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
%C Also numbers n such that (73*10^n+53)/9 is prime.
%C a(12) > 10^5. - _Robert Price_, Oct 09 2015
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/8/81117.htm#prime">Prime numbers of the form 811...117</a>.
%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F a(n) = A101059(n) + 1.
%t Do[ If[ PrimeQ[(73*10^n + 53)/9], Print[n]], {n, 0, 10000}]
%o (PARI) for(n=1, 1e6, if(isprime((73*10^n+53)/9), print1(n", "))) \\ _Altug Alkan_, Oct 09 2015
%Y Cf. A002275, A101059.
%K nonn
%O 1,1
%A _Robert G. Wilson v_, Jan 19 2005
%E a(9) from Kamada data by _Robert Price_, Dec 14 2010
%E a(10) from Erik Branger May 01 2013 by _Ray Chandler_, Aug 16 2013
%E a(11) from _Robert Price_, Oct 09 2015
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