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 A015042 #4 Mar 30 2012 17:20:37
%S A015042 1,1,122,1787655,3167175688854,678916835046916685242,
%T A015042 17609365062977481891291808896932,
%U A015042 55265734103510888653163896029554175314160719
%N A015042 q-Catalan numbers (binomial version) for q=11.
%F A015042 {1 / (n+1)_q} {2 n choose n}_q.
%K A015042 nonn,easy
%O A015042 0,3
%A A015042 _Olivier Gérard_