Number of loopless tree-rooted planar maps with 4 vertices and n faces.

Terms

a(0) =0a(1) =4a(2) =135a(3) =1368a(4) =7350a(5) =28400a(6) =89073a(7) =241220a(8) =585057a(9) =1301420a(10) =2699125a(11) =5282172a(12) =9842430a(13) =17584416a(14) =30289835a(15) =50530680a(16) =81940901a(17) =129557940a(18) =200246795a(19) =303220720a(20) =450674190a(21) =658545360a(22) =947426925a(23) =1343646044a(24) =1880535825a(25) =2599922780a(26) =3553856649a(27) =4806611060