First column of A027537.A027546First column of A027537.Terms a(0) =1a(1) =3a(2) =19a(3) =201a(4) =3131a(5) =66883a(6) =1866103a(7) =65599089a(8) =2826880471a(9) =146161621491External referencesoeis: A027546