Number of unlabeled connected loopless multigraphs with n nodes of degree 3 or less and with single or double edges.

A303030

Number of unlabeled connected loopless multigraphs with n nodes of degree 3 or less and with single or double edges.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =12a(5) =22a(6) =68a(7) =166a(8) =534a(9) =1589a(10) =5464a(11) =18579a(12) =68320a(13) =255424a(14) =1000852a(15) =4018156a(16) =16671976a(17) =70890940a(18) =309439942a(19) =1381815168a(20) =6310880471a(21) =29428287639a(22) =140012980007a(23) =678970863717

External references