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 A077361 #9 Jan 03 2015 11:43:09
%S A077361 0,0,127,1021,10037,100057,1000033,10000079,100000037,1000000021,
%T A077361 10000000033,100000000057,1000000000039,10000000000037,
%U A077361 100000000000031,1000000000000037,10000000000000079,100000000000000021
%N A077361 Smallest n-digit prime whose external digits as well as internal digits form a prime, or 0 if no such number exists.
%C A077361 Conjecture: no entry is zero for n>2.
%H A077361 Harvey P. Dale, <a href="/A077361/b077361.txt">Table of n, a(n) for n = 0..500</a>
%t A077361 eifpQ[n_]:=Module[{idn=IntegerDigits[n]},PrimeQ[FromDigits[{First[ idn], Last[ idn]}]]&&PrimeQ[FromDigits[Rest[Most[idn]]]]]; ndp[pwr_]: = Module[ {p=NextPrime[10^pwr]},While[!eifpQ[p],p=NextPrime[p]];p]; Join[ {0,0}, Table[ndp[i],{i,2,20}]] (* _Harvey P. Dale_, Jan 03 2015 *)
%Y A077361 Cf. A069686, A077359, A077360, A077362.
%K A077361 base,hard,nonn
%O A077361 0,3
%A A077361 _Amarnath Murthy_, Nov 05 2002
%E A077361 More terms from _Sascha Kurz_, Jan 11 2003