Number of unoriented series-parallel networks with n elements and without multiple unit elements in parallel.

A339296

Number of unoriented series-parallel networks with n elements and without multiple unit elements in parallel.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =23a(6) =60a(7) =170a(8) =496a(9) =1505a(10) =4665a(11) =14772a(12) =47415a(13) =154093a(14) =505394a(15) =1671009a(16) =5561274a(17) =18615687a(18) =62624016a(19) =211605003a(20) =717823582a(21) =2443711716a(22) =8345934897a(23) =28587110560a(24) =98181058020a(25) =338029066457

External references