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 A068691 #12 May 02 2016 11:24:02
%S A068691 3,23,223,2003,20021,200003,2000003,20000003,200000069,2000000063,
%T A068691 20000000089,200000000041,2000000000003,20000000000021,
%U A068691 200000000000027,2000000000000021,20000000000000003,200000000000000003,2000000000000000221,20000000000000000401
%N A068691 Smallest n-digit prime with all even digits except the least significant digit.
%H A068691 Alois P. Heinz, <a href="/A068691/b068691.txt">Table of n, a(n) for n = 1..500</a>
%t A068691 evQ[n_]:=And@@EvenQ[Take[x=IntegerDigits[n],Length[x]-1]]; t={3}; Do[i=PrimePi[2*10^n]+1; While[!evQ[p=Prime[i]],i++]; AppendTo[t,p],{n,13}]; t (* _Jayanta Basu_, May 21 2013 *)
%Y A068691 Cf. A068690.
%K A068691 base,nonn
%O A068691 1,1
%A A068691 _Amarnath Murthy_, Mar 03 2002
%E A068691 More terms from _Sascha Kurz_, Mar 17 2002