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 | 1441 |
| 4 | 22624 |
| 5 | 253690 |
| 6 | 1324160 |
| 7 | 6962675 |
| 8 | 24325376 |
| 9 | 80776164 |
| 10 | 225474240 |
| 11 | 601191285 |
| 12 | 1366506400 |
| 13 | 3152419966 |
| 14 | 6455003584 |
| 15 | 12902747495 |
| 16 | 24381528320 |
| 17 | 45355096520 |
| 18 | 78794712576 |
| 19 | 137109487689 |
| 20 | 225795051360 |
| 21 | 369875389570 |