Number of unlabeled nonseparable (or 2-connected) planar graphs with n edges.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =2a(5) =4a(6) =7a(7) =16a(8) =41a(9) =108a(10) =320a(11) =1042a(12) =3575a(13) =13064a(14) =49938a(15) =197729a(16) =805991a(17) =3363084a(18) =14302891a(19) =61813285a(20) =270805177a(21) =1200460492a(22) =5376709415a(23) =24302430375a(24) =110745093999a(25) =508380790741