Number of unlabeled loopless multigraphs with n edges covering four vertices.

Terms

a(0) =0a(1) =1a(2) =3a(3) =7a(4) =13a(5) =25a(6) =40a(7) =65a(8) =99a(9) =146a(10) =208a(11) =294a(12) =399a(13) =538a(14) =711a(15) =926a(16) =1188a(17) =1513a(18) =1896a(19) =2361a(20) =2910a(21) =3557a(22) =4312a(23) =5199a(24) =6214a(25) =7392a(26) =8739a(27) =10276a(28) =12019a(29) =14002