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 A110788 #7 Nov 14 2021 12:39:39 %S A110788 7,1,77,1111,77777,1111111111,77777777777777777777777, %T A110788 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 %N A110788 Copies of 7 and 1 alternately such that every partial concatenation is a prime. %e A110788 7, 71, 7177, 71771111, ... are all prime. %Y A110788 Cf. A110774, A110775, A110776, A110777, A110778, A110780, A110781, A110782, A110783, A110789. %K A110788 base,nonn %O A110788 1,1 %A A110788 _Amarnath Murthy_, Aug 13 2005 %E A110788 More terms from _Joshua Zucker_, Jan 11 2006