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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 694 |
| 7 | 4581 |
| 8 | 33285 |
| 9 | 260886 |
| 10 | 2173374 |
| 11 | 19032746 |
| 12 | 173741467 |
| 13 | 1642533692 |
| 14 | 15999488304 |
| 15 | 159917206735 |
| 16 | 1634681988983 |
| 17 | 17042352950764 |
| 18 | 180798150762914 |
| 19 | 1948027746498015 |
| 20 | 21282786390947602 |
| 21 | 235446451502773103 |
| 22 | 2634317655935012208 |
| 23 | 29778833170013213300 |