%I
%S 15,346,1137,1429,11143,21139
%N Numbers n such that the first n digits of the string nnnn... correspond to a prime number.
%C The primality of the numbers corresponding to the first 4 entries has been certified with Primo.
%e n=15 is in the sequence since the 15digit number 151515151515151 is prime.
%t f[n_]:=Block[{d=IntegerDigits@n},FromDigits@d[[Mod[Range@n  1,Length@d]+1]]]; Select[Range@1500,PrimeQ@f@# &]
%Y Subsequence of A171491.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, Sep 11 2012
