%I #15 Sep 14 2013 13:39:38
%S 1,2,12,13,15,17,121,3,131,5,151,7,171,21,31,51,71,212,1212,1213,1215,
%T 1217,1312,1313,1315,1317,1512,1513,1515,1517,1712,1713,1715,1717,
%U 12121,213,12131,215,12151,217,12171,312,13121,313,13131,315,13151,317,13171
%N Starting with 1, smallest integer not yet in the sequence such that two neighboring digits of the sequence multiply to a prime.
%K nonn,base
%O 1,2
%A _Eric Angelini_ and _Jim Nastos_, Apr 22 2012