Number of certain rooted planar maps.

Terms

a(0) =1a(1) =4a(2) =18a(3) =89a(4) =466a(5) =2537a(6) =14209a(7) =81316a(8) =473338a(9) =2793454a(10) =16674417a(11) =100487896a(12) =610549829a(13) =3735850007a(14) =23000055178a(15) =142370597601a(16) =885521350882