%I A034819
%S A034819 51,63,123,597,687,987,4429,12237,18291,20013,29953,31863,34653,48023,
%T A034819 52703,57147,59337,62097,66727,71733,81263,86589,101211,105501,118617,
%U A034819 121397,134013,146191,147151,155937,174723,175797,179191,180189,205287
%N A034819 Concatenations C1 and C2 and C3 and C4 are all prime (see the comment 
               lines).
%C A034819 C1 = 'nextprime(n) followed by n'
%C A034819 C2 = 'n followed by nextprime(n)'
%C A034819 C3 = 'prevprime(n) followed by n'
%C A034819 C4 = 'n followed by prevprime(n)'
%e A034819 n=105501 -> next prime is 105503, previous prime is 105499, thus '105503105501' 
               and '105501105503' and '105501105499' and '105499105501' are all 
               four primes.
%Y A034819 Cf. A034808-A034821.
%Y A034819 Sequence in context: A043990 A045068 A050701 this_sequence A118147 A015863 
               A113285
%Y A034819 Adjacent sequences: A034816 A034817 A034818 this_sequence A034820 A034821 
               A034822
%K A034819 nonn,base
%O A034819 0,1
%A A034819 Patrick De Geest (pdg(AT)worldofnumbers.com), Oct 15 1998.