%I A121609
%S A121609 22,25,27,32,33,35,52,55,57,72,75,77,112,115,117,132,133,135,172,175,
%T A121609 177,192,195,213,217,219,231,232,235,237,243,247,253,259,261,267,273,
%U A121609 279,289,292,295,297,312,315,319,323,329,341,343,361,371,372,375,377
%N A121609 Composite numbers that can be written as concatenation of two primes 
               in decimal representation.
%C A121609 Subsequence of A066737.
%e A121609 A002808(249) = 315 = 31*10+5 = A000040(11)*10+A000040(3),
%e A121609 therefore 315 is a term: a(44) = 315;
%e A121609 A002808(252) = 319 = 3*100+19 = A000040(2)*100+A000040(8),
%e A121609 therefore 319 is a term: a(45) = 319.
%Y A121609 Cf. A121610, A105184, A121608.
%Y A121609 Sequence in context: A053779 A034304 A066737 this_sequence A092631 A061371 
               A070809
%Y A121609 Adjacent sequences: A121606 A121607 A121608 this_sequence A121610 A121611 
               A121612
%K A121609 nonn,base
%O A121609 1,1
%A A121609 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 10 2006