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 A036951 #15 Mar 09 2020 09:13:06
%S A036951 0,89,0,8999,89899,888989,8888989,88888999,888898889,8888888989,
%T A036951 88888888999,888888898999,8888888999899,88888888888889,
%U A036951 888888888898999,8888888888989999,88888888888888889,888888888888898889
%N A036951 Smallest n-digit prime containing only the digits 8 and 9, or 0 if no such prime exists.
%H A036951 Jinyuan Wang, <a href="/A036951/b036951.txt">Table of n, a(n) for n = 1..500</a>
%t A036951 Table[SelectFirst[10#+9&/@FromDigits/@Tuples[{8,9},n-1],PrimeQ],{n,20}]/. (Missing["NotFound"]->0) (* _Harvey P. Dale_, Feb 01 2018 *)
%Y A036951 Cf. A020472, A036229, A036325.
%K A036951 nonn,base
%O A036951 1,2
%A A036951 _Patrick De Geest_, Jan 04 1999