Number of edge-rooted unlabeled graphs with n edges.

Terms

a(0) =1a(1) =2a(2) =7a(3) =21a(4) =66a(5) =210a(6) =699a(7) =2387a(8) =8492a(9) =31329a(10) =120034a(11) =477028a(12) =1965016a(13) =8377888a(14) =36923184a(15) =167972182a(16) =787688821a(17) =3802526173a(18) =18873118341a(19) =96195592212a(20) =502953711022