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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 60 |
| 6 | 900 |
| 7 | 8400 |
| 8 | 63000 |
| 9 | 417120 |
| 10 | 2551560 |
| 11 | 14804700 |
| 12 | 82764900 |
| 13 | 450518460 |
| 14 | 2404510500 |
| 15 | 12646078200 |
| 16 | 65771496000 |
| 17 | 339165516120 |
| 18 | 1737486149760 |
| 19 | 8855359634100 |
| 20 | 44952367981500 |
| 21 | 227475768907860 |
| 22 | 1148269329527100 |
| 23 | 5785013373810000 |
| 24 | 29100047092479000 |