%I A032721
%S A032721 5,6,8,12,15,17,21,29,32,33,35,39,44,45,50,51,54,56,59,63,65,78,81,87,
%T A032721 93,95,96,98,101,104,105,107,111,117,122,125,135,138,146,150,159,161,
%U A032721 162,164,168,173,177,188,189,192,194,195,201,215,218,219,222,225
%N A032721 n prefixed by '4' and followed by '7' is a prime.
%Y A032721 Sequence in context: A048583 A047321 A033158 this_sequence A105106 A140504 
               A120131
%Y A032721 Adjacent sequences: A032718 A032719 A032720 this_sequence A032722 A032723 
               A032724
%K A032721 nonn,base
%O A032721 0,1
%A A032721 Patrick De Geest (pdg(AT)worldofnumbers.com), May 15, 1998.