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 | 1 |
| 3 | 1 |
| 4 | 6 |
| 5 | 4 |
| 6 | 22 |
| 7 | 96 |
| 8 | 1344 |
| 9 | 672 |
| 10 | 3448 |
| 11 | 12114 |
| 12 | 158424 |
| 13 | 406312 |
| 14 | 4579440 |
| 15 | 37826256 |
| 16 | 906545760 |
| 17 | 362618304 |
| 18 | 1784113248 |
| 19 | 5576251408 |
| 20 | 68998853808 |
| 21 | 154939065862 |