Number of tree-rooted bridgeless planar maps with two vertices and n faces.

A002740

Number of tree-rooted bridgeless planar maps with two vertices and n faces.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =2a(4) =15a(5) =84a(6) =420a(7) =1980a(8) =9009a(9) =40040a(10) =175032a(11) =755820a(12) =3233230a(13) =13728792a(14) =57946200a(15) =243374040a(16) =1017958725a(17) =4242920400a(18) =17631691440a(19) =73078721100a(20) =302202005490

External references