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

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =7a(10) =8a(11) =9a(12) =36a(13) =40a(14) =44a(15) =110a(16) =120a(17) =130a(18) =338a(19) =371a(20) =405a(21) =1260a(22) =1400a(23) =1547a(24) =4760a(25) =5292a(26) =5852a(27) =16929a(28) =18780a(29) =20734