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 A036929 #9 Mar 09 2020 09:12:22 %S A036929 0,11,101,0,10111,101111,1011001,10010101,100100111,1000001011, %T A036929 10000001101,100000001111,1000000111001,10000000001011, %U A036929 100000000100101,1000000000011101,10000000000001101,100000000000100111 %N A036929 Smallest n-digit prime containing only digits 0 and 1, or 0 if no such prime exists. %H A036929 Jinyuan Wang, <a href="/A036929/b036929.txt">Table of n, a(n) for n = 1..500</a> %o A036929 (PARI) a(n) = for(k=2^(n-1), 2^n-1, v=binary(k); if(ispseudoprime(p=fromdigits(v)), return(p))); 0; \\ _Jinyuan Wang_, Mar 09 2020 %Y A036929 Cf. A020449, A036229, A036928. %K A036929 nonn,base %O A036929 1,2 %A A036929 _Patrick De Geest_, Jan 04 1999