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) =5a(8) =6a(9) =7a(10) =28a(11) =32a(12) =36a(13) =90a(14) =100a(15) =110a(16) =275a(17) =306a(18) =338a(19) =1001a(20) =1127a(21) =1260a(22) =3780a(23) =4256a(24) =4760a(25) =13532a(26) =15180a(27) =16929a(28) =47880a(29) =53700