Number of nonempty subsets of {1,2,...,n} in which exactly 3/4 of the elements are <= (n-1)/2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =4a(7) =5a(8) =20a(9) =24a(10) =60a(11) =70a(12) =161a(13) =188a(14) =476a(15) =567a(16) =1512a(17) =1820a(18) =4740a(19) =5709a(20) =14520a(21) =17500a(22) =44572a(23) =53911a(24) =138567a(25) =168245a(26) =433433a(27) =527540a(28) =1355900a(29) =1652924