Number of nonempty subsets of {1..n} with mean n/2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =3a(5) =3a(6) =9a(7) =8a(8) =25a(9) =23a(10) =75a(11) =68a(12) =235a(13) =213a(14) =759a(15) =695a(16) =2521a(17) =2325a(18) =8555a(19) =7941a(20) =29503a(21) =27561a(22) =103129a(23) =96861a(24) =364547a(25) =344003a(26) =1300819a(27) =1232566a(28) =4679471a(29) =4449849