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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 2640 |
| 8 | 13596 |
| 9 | 87768 |
| 10 | 680274 |
| 11 | 6090756 |
| 12 | 61678252 |
| 13 | 482005340 |
| 14 | 4454053680 |
| 15 | 46705656280 |
| 16 | 549750105234 |