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 | 0 |
| 2 | 240 |
| 3 | 1584 |
| 4 | 9720 |
| 5 | 54936 |
| 6 | 299088 |
| 7 | 1585800 |
| 8 | 8244288 |
| 9 | 42216696 |
| 10 | 213602256 |
| 11 | 1070280936 |
| 12 | 5319700704 |
| 13 | 26262038232 |
| 14 | 128900271600 |
| 15 | 629516497608 |
| 16 | 3061019061504 |
| 17 | 14827169463480 |
| 18 | 71576870716944 |
| 19 | 344483107968168 |