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

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =4a(5) =4a(6) =14a(7) =14a(8) =49a(9) =49a(10) =175a(11) =175a(12) =637a(13) =637a(14) =2353a(15) =2353a(16) =8788a(17) =8788a(18) =33098a(19) =33098a(20) =125476a(21) =125476a(22) =478192a(23) =478192a(24) =1830270a(25) =1830270a(26) =7030570a(27) =7030570a(28) =27088870a(29) =27088870