%I A103063
%S A103063 1,2,6,25,69,253,300,384,434,721,822,883,2192,2649,3441,3445,8028
%N A103063 Numbers n such that 7*10^n + 6*R_n - 5 is prime, where R_n = 11...1 is 
               the repunit (A002275) of length n.
%C A103063 Also numbers n such that (23*10^n-17)/3 is prime.
%H A103063 Makoto Kamada, <a href="http://homepage2.nifty.com/m_kamada/math/76661.htm">
               Factorizations of 766...661</a>.
%H A103063 <a href="Sindx_Pri.html#Pri_rep">Index entries for primes involving repunits</
               a>.
%t A103063 Do[ If[ PrimeQ[(23*10^n - 17)/3], Print[n]], {n, 0, 10000}]
%Y A103063 Sequence in context: A123150 A086591 A073545 this_sequence A030228 A066317 
               A027104
%Y A103063 Adjacent sequences: A103060 A103061 A103062 this_sequence A103064 A103065 
               A103066
%K A103063 more,nonn
%O A103063 1,2
%A A103063 Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005