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 A253245 #104 Nov 29 2015 09:41:43
%S A253245 37,1117,1319,1723,4759,89101,97103,101107,113131,151163,181193,
%T A253245 223229,227233,239251,251263,293311,313331,337349,389401,421433,
%U A253245 461467,491503,587599,631643,647659,683701,691709,701719,739751,761773,809821
%N A253245 Primes that are the concatenation of prime(n) and prime(n+2).
%H A253245 Harvey P. Dale, <a href="/A253245/b253245.txt">Table of n, a(n) for n = 1..1000</a>
%t A253245 Module[{nn=300,pr},pr={#[[1]],#[[3]]}&/@Partition[Prime[Range[nn]],3,1];Select[Table[FromDigits[Flatten[IntegerDigits/@pr[[n]]]],{n, Length[ pr]}],PrimeQ]] (* _Harvey P. Dale_, Nov 29 2015 *)
%o A253245 (PARI) for(n=1, 1e3, if(isprime(k=eval(Str(prime(n), prime(n+2)))), print1(k", ")))
%Y A253245 Cf. A000040, A030461.
%K A253245 nonn,easy,base
%O A253245 1,1
%A A253245 _Altug Alkan_, Aug 22 2015