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 | 2 |
| 5 | 7 |
| 6 | 28 |
| 7 | 131 |
| 8 | 720 |
| 9 | 4513 |
| 10 | 31824 |
| 11 | 249513 |
| 12 | 2151744 |
| 13 | 20242983 |
| 14 | 206313024 |
| 15 | 2264425179 |
| 16 | 26628836352 |
| 17 | 334022337153 |
| 18 | 4451717814528 |
| 19 | 62820790592913 |
| 20 | 935750983412736 |
| 21 | 14672143677452679 |
| 22 | 241555066200437760 |