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 | 108 |
| 6 | 596 |
| 7 | 3674 |
| 8 | 26068 |
| 9 | 202470 |
| 10 | 1753884 |
| 11 | 16435754 |
| 12 | 168174596 |
| 13 | 1842418704 |
| 14 | 21757407158 |
| 15 | 272771715272 |
| 16 | 3649515044178 |
| 17 | 51532670206504 |
| 18 | 770442883634326 |
| 19 | 12093451621846094 |
| 20 | 199856952123506304 |
| 21 | 3452120352032161404 |
| 22 | 62471981051497913826 |
| 23 | 1177664861561125869100 |
| 24 | 23163177237781937250558 |