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 | 5 |
| 3 | 30 |
| 4 | 200 |
| 5 | 1435 |
| 6 | 10900 |
| 7 | 86799 |
| 8 | 720074 |
| 9 | 6196295 |
| 10 | 55135043 |
| 11 | 506125404 |
| 12 | 4784680169 |
| 13 | 46516469860 |
| 14 | 464550190798 |
| 15 | 4761343733469 |
| 16 | 50044839978614 |
| 17 | 539051253692777 |
| 18 | 5946806890025709 |
| 19 | 67156408547628636 |
| 20 | 775935817487472046 |