A360881 Number of unlabeled nonseparable (or 2-connected) multigraphs with n edges, loops allowed.
1, 2, 5, 9, 19, 44, 111, 328, 1090, 3988, 15838, 67295, 301417, 1412821, 6882398, 34682721, 180170661, 962288228, 5273162329
Offset: 1
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.