Number of geodetic graphs with n unlabeled vertices.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =23a(6) =66a(7) =185a(8) =586a(9) =1880a(10) =6360a(11) =21975a(12) =78230a(13) =283087a(14) =1043329a(15) =3895505a(16) =14726263a(17) =56234210a(18) =216719056a(19) =841857211a(20) =3293753840a(21) =12969219563