This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A211683 #6 Jan 04 2013 14:57:44 %S A211683 111,113,117,119,131,137,171,173,179,197,231,237,297,311,313,317,319, %T A211683 371,373,379,411,413,417,419,431,437,471,473,479,531,537,597,611,613, %U A211683 617 %N A211683 Numbers > 100 such that all the substrings of length = 2 are primes. %C A211683 Only numbers > 100 are considered, since all 2-digit primes are trivial members. See A069488 for the sequence with prime terms > 100. %C A211683 The sequence is infinite (for example, consider the continued concatenation of ‘11’ or of ‘13’: 111, 1111, 11111, ..., 131, 1313, 13131, ... are members). %C A211683 Infinitely many terms are palindromic. %H A211683 Hieronymus Fischer, <a href="/A211683/b211683.txt">Table of n, a(n) for n = 1..5000</a> %e A211683 a(2)=113, since all substrings of length = 2 are primes (11 and 13). %e A211683 a(10)=197, since all substrings of length = 2 (19, 97) are primes. %Y A211683 Cf. A019546, A035232, A039996, A046034, A069488, A085823, A131648, A211681, A211682. %K A211683 nonn,base %O A211683 1,1 %A A211683 _Hieronymus Fischer_, Jun 08 2012