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 | 2 |
| 4 | 6 |
| 5 | 22 |
| 6 | 99 |
| 7 | 520 |
| 8 | 3126 |
| 9 | 21164 |
| 10 | 159226 |
| 11 | 1318000 |
| 12 | 11902268 |
| 13 | 116444668 |
| 14 | 1226878267 |
| 15 | 13849980752 |
| 16 | 166773534726 |
| 17 | 2133706472788 |
| 18 | 28904542964982 |
| 19 | 413312731986464 |
| 20 | 6221110588709700 |
| 21 | 98321023508946088 |
| 22 | 1627902016045648206 |
| 23 | 28178332753660846304 |