Number of graphs with n nodes, n edges and no isolated vertices.

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =2a(5) =5a(6) =15a(7) =41a(8) =124a(9) =369a(10) =1132a(11) =3491a(12) =10984a(13) =34768a(14) =111514a(15) =360560a(16) =1176797a(17) =3870389a(18) =12829765a(19) =42829894a(20) =143980892a(21) =487227611a(22) =1659499566a(23) =5688046485a(24) =19617965938a(25) =68078878268a(26) =237694501644a(27) =834946053269