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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 28 |
| 6 | 111 |
| 7 | 539 |
| 8 | 3150 |
| 9 | 21623 |
| 10 | 172349 |
| 11 | 1549897 |
| 12 | 15401145 |
| 13 | 168011253 |
| 14 | 2003304294 |
| 15 | 25928878273 |
| 16 | 361788001016 |
| 17 | 5411160126368 |
| 18 | 86353882249912 |
| 19 | 1464841397585336 |
| 20 | 26323224850512720 |
| 21 | 499551889319197566 |