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

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =7a(5) =22a(6) =76a(7) =271a(8) =1001a(9) =3765a(10) =14381a(11) =55450a(12) =214880a(13) =835663a(14) =3255652a(15) =12698352a(16) =49559793a(17) =193513944a(18) =755852101a(19) =2953214386a(20) =11541989533a(21) =45123241746a(22) =176465152051a(23) =690340349398