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 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 40320 |
| 9 | 287280 |
| 10 | 1865520 |
| 11 | 11345160 |
| 12 | 66349464 |
| 13 | 381523758 |
| 14 | 2193664790 |
| 15 | 12764590275 |
| 16 | 75796724309 |
| 17 | 455383613924 |
| 18 | 2750869551868 |
| 19 | 16635586999056 |
| 20 | 100439873614656 |
| 21 | 604666567043712 |
| 22 | 3629299734118656 |
| 23 | 21736009354060800 |
| 24 | 130082373922081536 |