Number of unsensed planar maps with n vertices and 2 faces.

Terms

a(0) =1a(1) =2a(2) =5a(3) =13a(4) =35a(5) =104a(6) =315a(7) =1021a(8) =3407a(9) =11814a(10) =41893a(11) =151688a(12) =556432a(13) =2063446a(14) =7709381a(15) =28977788a(16) =109421539a(17) =414759097a(18) =1577080457a(19) =6013019088a(20) =22980514005a(21) =88012484058a(22) =337717418145