Number of non-isomorphic connected set systems of weight n with empty intersection.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =2a(6) =9a(7) =22a(8) =69a(9) =190a(10) =567a(11) =1640a(12) =5025a(13) =15404a(14) =49048a(15) =159074a(16) =531165a(17) =1813627a(18) =6352739a(19) =22759620a(20) =83443086a(21) =312612543a(22) =1196356133a(23) =4672620842a(24) =18615188819a(25) =75593464871a(26) =312729620542