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 A088073 #8 Nov 18 2017 20:59:29 %S A088073 11,3,777,999,11,131313131313131313131313131313131313131313 %N A088073 Beginning with 11 (concatenation of 1 twice), smallest number which is a concatenation of itself as many (say k) times required, chosen from odd numbers not == 5 (mod 10), in natural order, so that every partial concatenation is prime. %C A088073 Numbers chosen are from 1,3,7,9,11,13,17,19,21,23,27,29,... which can produce primes. %C A088073 Next term has > 2000 digits and is too large to include. - _David Wasserman_, Jul 01 2005 %Y A088073 Cf. A088074. %K A088073 base,nonn %O A088073 0,1 %A A088073 _Amarnath Murthy_, Sep 22 2003 %E A088073 More terms from _David Wasserman_, Jul 01 2005