A048071 Number of nonempty subsets of {1,2,...,n} in which exactly 1/2 of the elements are <= (n+2)/3.

0, 1, 2, 5, 9, 14, 34, 55, 83, 209, 329, 494, 1286, 2001, 3002, 8007, 12375, 18563, 50387, 77519, 116279, 319769, 490313, 735470, 2042974, 3124549, 4686824, 13123109, 20030009, 30045014, 84672314, 129024479, 193536719