Number of unlabeled loopless multigraphs with 4 nodes of degree n or less.

Terms

a(0) =1a(1) =3a(2) =10a(3) =26a(4) =61a(5) =128a(6) =254a(7) =467a(8) =821a(9) =1376a(10) =2224a(11) =3470a(12) =5269a(13) =7785a(14) =11254a(15) =15930a(16) =22149a(17) =30276a(18) =40786a(19) =54177a(20) =71089a(21) =92198a(22) =118336a(23) =150386a(24) =189425a(25) =236573a(26) =293186a(27) =360680a(28) =440725a(29) =535070