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 | 5 |
| 4 | 24 |
| 5 | 35 |
| 6 | 17304 |
| 7 | 105210 |
| 8 | 15002667388800 |
| 9 | 2803962610087320 |
| 10 | 390995845903819693817280 |
| 11 | 4427769139935736194600 |
| 12 | 426341479886584667397117049422960 |