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%I #19 Jan 17 2019 13:44:07
%S 2,3,32,42,75,368,1392,16350,49101,49689,91839
%N Numbers n such that 9*10^n + 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
%C Also numbers n such that (89*10^n-53)/9 is prime.
%C a(12) > 10^5. - _Robert Price_, Nov 12 2015
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/9/98883.htm#prime">Prime numbers of the form 988...883</a>.
%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F a(n) = A101017(n) + 1.
%t Do[ If[ PrimeQ[(89*10^n - 53)/9], Print[n]], {n, 0, 10000}]
%Y Cf. A002275, A101017.
%K more,nonn
%O 1,1
%A _Robert G. Wilson v_, Jan 19 2005
%E a(8) from Kamada data by _Robert Price_, Dec 14 2010
%E a(9)-a(10) from Erik Branger May 01 2013 by _Ray Chandler_, Aug 17 2013
%E a(11) from _Robert Price_, Nov 12 2015
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