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 A086923 #4 Dec 05 2013 19:56:20 %S A086923 11,331,2221,33331,333331,3333331,33333331,30303030303030301, %T A086923 6666666661,44444444441,555555555551,5555555555551, %U A086923 252525252525252525252525251,42424242424242424242424242421,1717171717171717171717171717171 %N A086923 Primes arising in A086920, or 0 if A086920(n) = 0. %Y A086923 Cf. A086920, A087604, A087605, A087606, A087607, A087608, A087609. %K A086923 base,nonn %O A086923 1,1 %A A086923 _Amarnath Murthy_, Sep 18 2003 %E A086923 More terms from _David Wasserman_, Apr 12 2005