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 | 120 |
| 7 | 2160 |
| 8 | 23940 |
| 9 | 211680 |
| 10 | 1643544 |
| 11 | 11748240 |
| 12 | 79419060 |
| 13 | 516257280 |
| 14 | 3262440960 |
| 15 | 20193277104 |
| 16 | 123071683140 |
| 17 | 741419995680 |
| 18 | 4427489935680 |
| 19 | 26264144909520 |
| 20 | 155018839412052 |
| 21 | 911509010152560 |
| 22 | 5344538372696880 |
| 23 | 31272099902089200 |
| 24 | 182707081042818360 |