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2n repeated C_n times, where C_n = A000108(n) is a Catalan number.
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%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