Number of isomorphism classes of simple quadrangulations of the sphere having n vertices and n-2 faces, with orientation-reversing isomorphisms permitted.

A113201

Number of isomorphism classes of simple quadrangulations of the sphere having n vertices and n-2 faces, with orientation-reversing isomorphisms permitted.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =3a(4) =9a(5) =18a(6) =62a(7) =198a(8) =803a(9) =3378a(10) =15882a(11) =77185a(12) =393075a(13) =2049974a(14) =10938182a(15) =59312272a(16) =326258544a(17) =1815910231a(18) =10213424233a(19) =57974895671a(20) =331820721234

External references