Number of unrooted two-vertex n-edge maps in the plane (planar with a distinguished outside face).

A103943

Number of unrooted two-vertex n-edge maps in the plane (planar with a distinguished outside face).

Terms

    a(0) =1a(1) =3a(2) =12a(3) =48a(4) =196a(5) =798a(6) =3248a(7) =13184a(8) =53416a(9) =216018a(10) =872344a(11) =3518496a(12) =14177528a(13) =57080572a(14) =229657792a(15) =923474944a(16) =3711572176a(17) =14911097514a(18) =59883185096a(19) =240416320928a(20) =964947251544

External references