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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 26 |
| 5 | 133 |
| 6 | 708 |
| 7 | 3861 |
| 8 | 21604 |
| 9 | 123266 |
| 10 | 715221 |
| 11 | 4206956 |
| 12 | 25032840 |
| 13 | 150413348 |
| 14 | 911379384 |
| 15 | 5562367173 |
| 16 | 34164355848 |
| 17 | 211015212580 |
| 18 | 1309815397995 |
| 19 | 8166460799805 |
| 20 | 51120054233490 |
| 21 | 321156223592865 |
| 22 | 2024257417812240 |
| 23 | 12797201858645100 |