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 | 0 |
| 6 | 0 |
| 7 | 5040 |
| 8 | 322560 |
| 9 | 6531840 |
| 10 | 72576000 |
| 11 | 548856000 |
| 12 | 3161410560 |
| 13 | 14841066240 |
| 14 | 59364264960 |
| 15 | 208702494000 |
| 16 | 659602944000 |
| 17 | 1906252508160 |
| 18 | 5104345559040 |
| 19 | 12796310741760 |
| 20 | 30287126016000 |
| 21 | 68146033536000 |