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.
| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 9 |
| 2 | 41 |
| 3 | 189 |
| 4 | 881 |
| 5 | 4149 |
| 6 | 19721 |
| 7 | 94509 |
| 8 | 456161 |
| 9 | 2215269 |
| 10 | 10814201 |
| 11 | 53022429 |
| 12 | 260917841 |
| 13 | 1287811989 |
| 14 | 6371951081 |
| 15 | 31591319949 |
| 16 | 156882857921 |
| 17 | 780119322309 |
| 18 | 3883416742361 |
| 19 | 19348364235069 |
| 20 | 96466943268401 |
| 21 | 481235204714229 |