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 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 21 |
| 4 | 84 |
| 5 | 425 |
| 6 | 2586 |
| 7 | 18137 |
| 8 | 145096 |
| 9 | 1305873 |
| 10 | 13058830 |
| 11 | 143647141 |
| 12 | 1723765788 |
| 13 | 22408955257 |
| 14 | 313725373682 |
| 15 | 4705880605425 |
| 16 | 75294089686800 |
| 17 | 1279999524675617 |
| 18 | 23039991444161430 |
| 19 | 437759837439067189 |
| 20 | 8755196748781343780 |
| 21 | 183859131724408219737 |
| 22 | 4044900897936980834346 |