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 A211682 #15 Oct 08 2018 04:17:15 %S A211682 2,3,5,7,23,37,53,73,373,237373,537373,5373737,53737373,53737373737, %T A211682 237373737373,737373737373737,53737373737373737,373737373737373737373, %U A211682 53737373737373737373737,53737373737373737373737373,373737373737373737373737373,5373737373737373737373737373737 %N A211682 Prime numbers such that all the substrings of length <= 2 are primes. %C A211682 A211681 restricted to primes. Contains A085823. In contrast to A085823 this sequence seems to be not finite (conjecture). %H A211682 Giovanni Resta, <a href="/A211682/b211682.txt">Table of n, a(n) for n = 1..36</a> (terms < 10^1000) %e A211682 a(10)=237373, since all substrings of length <= 2 are primes (2, 3, 7, 23, 37, 73) and 237373 is prime. %Y A211682 Cf. A085823, A019546, A046034, A211681. %K A211682 nonn,base %O A211682 1,1 %A A211682 _Hieronymus Fischer_, Apr 30 2012 %E A211682 The originally submitted terms with index 20 and 21 are composite and have been erased therefore. - _Hieronymus Fischer_, Sep 24 2018 %E A211682 a(20)-a(22) from _Giovanni Resta_, Oct 08 2018