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%I #20 Jan 17 2019 13:44:07
%S 0,1,2,3,13,19,62,80,126,168,195,309,410,481,608,741,879,1176,2688,
%T 6236,16294,17317,31574,34861,35392,48726
%N Numbers n such that 8*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
%C Also numbers n such that (26*10^n-11)/3 is prime.
%C a(27) > 10^5. - _Robert Price_, Oct 25 2015
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/8/86663.htm#prime">Prime numbers of the form 866...663</a>.
%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F a(n) = A101074(n-1) + 1, for n>1.
%t Do[ If[ PrimeQ[(26*10^n - 11)/3], Print[n]], {n, 0, 10000}]
%Y Cf. A002275, A101074.
%K more,nonn
%O 1,3
%A _Robert G. Wilson v_, Jan 19 2005
%E a(21)-a(22) from Kamada data by _Robert Price_, Dec 14 2010
%E a(23)-a(26) from Erik Branger May 01 2013 by _Ray Chandler_, Aug 16 2013
%E Inserted a(1)=0 by _Robert Price_, Oct 25 2015
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