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 | 5040 |
| 8 | 315 |
| 9 | 2835 |
| 10 | 28350 |
| 11 | 311850 |
| 12 | 3742200 |
| 13 | 48648600 |
| 14 | 681080400 |
| 15 | 10216206000 |
| 16 | 1277025750 |
| 17 | 21709437750 |
| 18 | 178678500 |
| 19 | 3394891500 |
| 20 | 67897830000 |
| 21 | 1425854430000 |
| 22 | 31368797460000 |
| 23 | 721482341580000 |
| 24 | 135277939046250 |
| 25 | 3381948476156250 |