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 | 2 |
| 3 | 5 |
| 4 | 20 |
| 5 | 230 |
| 6 | 26795 |
| 7 | 359026205 |
| 8 | 64449908476890320 |
| 9 | 2076895351339769460477611370186680 |
| 10 | 2156747150208372213435450937462082366919951682912789656986079991220 |