Number of knot diagrams of type 2PI with n crossings and two outgoing strings.

A067648

Number of knot diagrams of type 2PI with n crossings and two outgoing strings.

Terms

    a(0) =0a(1) =2a(2) =0a(3) =2a(4) =4a(5) =12a(6) =60a(7) =226a(8) =1076a(9) =5156a(10) =24984a(11) =128548a(12) =663040a(13) =3514968a(14) =18918792a(15) =103123906a(16) =569877652a(17) =3180066004a(18) =17921451960a(19) =101842206548a(20) =583109887600

External references