Number of non-isomorphic set-systems of weight n with no endpoints.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =0a(6) =4a(7) =4a(8) =16a(9) =26a(10) =87a(11) =181a(12) =570a(13) =1453a(14) =4464a(15) =13038a(16) =41548a(17) =132217a(18) =442603a(19) =1506803a(20) =5305174a(21) =19092816a(22) =70548770a(23) =266495254a(24) =1029835424a(25) =4063610148a(26) =16366919221a(27) =67217627966a(28) =281326631801