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 A162550 #2 Mar 30 2012 17:35:23 %S A162550 0,2,4,4,6,6,6,6,6,8,8,8,8,8,8,8,8,8,8,8,8,8,8,10,10,10,10,10,10,10, %T A162550 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10, %U A162550 10,10,10,10,10,10,10,10,10,10,10,10,12,12,12,12,12,12,12,12,12,12,12,12 %N A162550 2n repeated C_n times, where C_n = A000108(n) is a Catalan number. %C A162550 Lengths of Dyck paths (A162549). %F A162550 a(n) = 2 * A072643(n). %Y A162550 Cf. A162549, A072643, A000108. %K A162550 nonn %O A162550 0,2 %A A162550 _Franklin T. Adams-Watters_, Jul 05 2009