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) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 24 |
| 5 | 240 |
| 6 | 2040 |
| 7 | 15120 |
| 8 | 106680 |
| 9 | 726768 |
| 10 | 4861560 |
| 11 | 32126160 |
| 12 | 210749880 |
| 13 | 1375923120 |
| 14 | 8955795576 |
| 15 | 58177326480 |
| 16 | 377439735480 |
| 17 | 2446686537840 |
| 18 | 15851581501560 |
| 19 | 102662600100432 |
| 20 | 664738663537080 |