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 | 4 |
| 4 | 63 |
| 5 | 720 |
| 6 | 7254 |
| 7 | 68460 |
| 8 | 621315 |
| 9 | 5496208 |
| 10 | 47759130 |
| 11 | 409620156 |
| 12 | 3478672642 |
| 13 | 29315742924 |
| 14 | 245539064736 |
| 15 | 2046309441924 |
| 16 | 16983591315267 |