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 A242377 #13 May 14 2014 06:25:51
%S A242377 7,97,971,9719,97973,979717,9797371,97973731,979797979,9797979713,
%T A242377 97979797171,979797973117,9797979797971,97979797973173,
%U A242377 979797979797317,9797979797979719,97979797979797373,979797979797971179,9797979797979737971
%N A242377 Greatest n-digit prime in which every two-digit string is also a prime.
%C A242377 To stay parallel with A090534, a(1) exists.
%C A242377 The greatest potential candidate, gpc(n), is of the form floor(10^n*97/99). The following is gpc(n)-a(n): 2, 0, 8, 78, 6, 80, 608, 6066, 0, 84, 808, 6680, 8, 6624, 662, 78, 606, 8618, 60008, 86, 600, 6000, 660, 608060, 808, ... .
%H A242377 Robert G. Wilson v, <a href="/A242377/b242377.txt">Table of n, a(n) for n = 1..100</a>
%t A242377 fQ[p_] := Block[{id = IntegerDigits@ p}, Union@ PrimeQ[ FromDigits@# & /@ Partition[id, 2, 1]] == {True}]; f[n_] := Block[{p = NextPrime[10^n*97/99, -1]}, While[ !fQ@ p, p = NextPrime[p, -1]]; p]; f[1] = 7; Array[f, 19]
%Y A242377 Cf. A090534, A069488.
%K A242377 nonn,base
%O A242377 1,1
%A A242377 _Robert G. Wilson v_, May 12 2014