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 A036934 #10 Mar 09 2020 05:39:25
%S A036934 7,11,0,1117,11117,0,1111711,11111117,0,1111117171,11111111771,0,
%T A036934 1111111111177,11111111171177,0,1111111111171177,11111111111111171,0,
%U A036934 1111111111111111111,11111111111111117111,0,1111111111111111111711
%N A036934 Smallest n-digit prime containing only digits 1 and 7, or 0 if no such prime exists.
%H A036934 Jinyuan Wang, <a href="/A036934/b036934.txt">Table of n, a(n) for n = 1..1000</a>
%t A036934 Flatten[Table[Select[FromDigits/@Tuples[{1, 7}, n], PrimeQ, 1], {n, 25}]/.{}->{0}] (* _Jinyuan Wang_, Mar 09 2020 *)
%Y A036934 Cf. A020455, A036307, A036229.
%K A036934 nonn,base
%O A036934 1,1
%A A036934 _Patrick De Geest_, Jan 04 1999
%E A036934 a(16) corrected by _Jinyuan Wang_, Mar 09 2020