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