A047176 Number of nonempty subsets of {1,2,...,n} in which exactly 1/5 of the elements are <= (n-1)/2.

0, 0, 0, 0, 0, 2, 3, 15, 20, 60, 75, 175, 210, 435, 511, 1071, 1260, 2940, 3510, 8910, 10725, 27345, 32835, 80795, 96382, 230230, 273273, 649805, 770315, 1860131, 2208115, 5426995, 6451500, 15974220