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

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =3a(6) =4a(7) =16a(8) =20a(9) =50a(10) =60a(11) =135a(12) =161a(13) =392a(14) =476a(15) =1232a(16) =1512a(17) =3864a(18) =4740a(19) =11850a(20) =14520a(21) =36300a(22) =44572a(23) =112519a(24) =138567a(25) =351351a(26) =433433a(27) =1098188a(28) =1355900a(29) =3433703