Number of 3-element ordered antichains on an unlabeled n-element set; T_1-hypergraphs with 3 labeled nodes and n hyperedges.

A056005

Number of 3-element ordered antichains on an unlabeled n-element set; T_1-hypergraphs with 3 labeled nodes and n hyperedges.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =2a(4) =19a(5) =90a(6) =302a(7) =820a(8) =1926a(9) =4068a(10) =7920a(11) =14454a(12) =25025a(13) =41470a(14) =66222a(15) =102440a(16) =154156a(17) =226440a(18) =325584a(19) =459306a(20) =636975a(21) =869858a(22) =1171390a(23) =1557468a(24) =2046770a(25) =2661100a(26) =3425760a(27) =4369950a(28) =5527197a(29) =6935814

External references