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 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 67 |
| 5 | 461 |
| 6 | 3823 |
| 7 | 36933 |
| 8 | 407963 |
| 9 | 5068909 |
| 10 | 69982083 |
| 11 | 1062784273 |
| 12 | 17607354955 |
| 13 | 316012688213 |
| 14 | 6108011298847 |
| 15 | 126490611884013 |
| 16 | 2794122884322635 |
| 17 | 65578524701197341 |
| 18 | 1629676370022564219 |
| 19 | 42748628870263418761 |
| 20 | 1180373377691425730235 |