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Number of nonempty subsets of {1,2,...,n} in which exactly 1/2 of the elements are <= n/3.
1

%I #9 Jun 04 2013 12:11:43

%S 0,0,2,3,4,14,20,27,83,119,164,494,714,1000,3002,4367,6187,18563,

%T 27131,38759,116279,170543,245156,735470,1081574,1562274,4686824,

%U 6906899,10015004,30045014,44352164,64512239,193536719,286097759

%N Number of nonempty subsets of {1,2,...,n} in which exactly 1/2 of the elements are <= n/3.

%F a(n) = C(n, [n/3]) - 1 = A051033(n) - 1. - _Ralf Stephan_, Mar 16 2004

%K nonn

%O 1,3

%A _Clark Kimberling_