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 | 60 |
| 7 | 1080 |
| 8 | 11970 |
| 9 | 105840 |
| 10 | 821952 |
| 11 | 5874480 |
| 12 | 39713550 |
| 13 | 258136200 |
| 14 | 1631273220 |
| 15 | 10096734312 |
| 16 | 61536377700 |
| 17 | 370710950400 |
| 18 | 2213749658880 |
| 19 | 13132080672480 |
| 20 | 77509456944318 |
| 21 | 455754569692680 |