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Number of nonempty subsets of {1,2,...,n} in which exactly 1/2 of the elements are <= (n+2)/3.
0

%I #4 Mar 30 2012 18:56:54

%S 0,1,2,5,9,14,34,55,83,209,329,494,1286,2001,3002,8007,12375,18563,

%T 50387,77519,116279,319769,490313,735470,2042974,3124549,4686824,

%U 13123109,20030009,30045014,84672314,129024479,193536719

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

%K nonn

%O 1,3

%A _Clark Kimberling_