%I A102992
%S A102992 1,2,4,5,13,22,25,28,38,67,142,284,295,380,397,1217,1640,2885,3286,7735
%N A102992 Numbers n such that 4*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is 
               the repunit (A002275) of length n.
%C A102992 Also numbers n such that (41*10^n+13)/9 is prime.
%H A102992 Makoto Kamada, <a href="http://homepage2.nifty.com/m_kamada/math/45557.htm">
               Factorizations of 455...557</a>.
%H A102992 <a href="Sindx_Pri.html#Pri_rep">Index entries for primes involving repunits</
               a>.
%t A102992 Do[ If[ PrimeQ[(41*10^n + 13)/9], Print[n]], {n, 0, 10000}]
%Y A102992 Sequence in context: A139485 A079407 A078652 this_sequence A136563 A127077 
               A104549
%Y A102992 Adjacent sequences: A102989 A102990 A102991 this_sequence A102993 A102994 
               A102995
%K A102992 more,nonn
%O A102992 1,2
%A A102992 Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005