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 | 0 |
| 8 | 0 |
| 9 | 362880 |
| 10 | 36288000 |
| 11 | 1097712000 |
| 12 | 17563392000 |
| 13 | 185513328000 |
| 14 | 1454424491520 |
| 15 | 9090153072000 |
| 16 | 47491411968000 |
| 17 | 214453407168000 |
| 18 | 857813628672000 |
| 19 | 3096707199505920 |
| 20 | 10237048593408000 |
| 21 | 31350961317312000 |