%I A069749
%S A069749 2,3,5,7,11,18,31,44,83,135,239,436,818,1436,2773,4695,9244,17022,
%T A069749 32948,58158,116040,214188
%N A069749 Number of primes less than 10^n containing only the digits 2 and 3 (A020458).
%C A069749 a(22) / A006880(22) = 214188 / 201467286689315906290 =~ 10^-15. But out 
               of the 2^22 candidates for primes, ~5% are.
%t A069749 s = 0; Do[k = 0; While[k < 2^n, k++; If[p = FromDigits[ PadLeft[ IntegerDigits[k, 
               2], n] + 2]; PrimeQ[p], s++ ]]; Print[s], {n, 1, 22}]
%Y A069749 Cf. A006880, A020458 & A036937.
%Y A069749 Sequence in context: A038887 A067904 A018146 this_sequence A081889 A078139 
               A120628
%Y A069749 Adjacent sequences: A069746 A069747 A069748 this_sequence A069750 A069751 
               A069752
%K A069749 base,nonn
%O A069749 1,1
%A A069749 Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 22 2002