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 | 2 |
| 2 | 2 |
| 3 | 3 |
| 4 | 3 |
| 5 | 45 |
| 6 | 45 |
| 7 | 561330 |
| 8 | 9549960 |
| 9 | 42932385 |
| 10 | 13044904290 |
| 11 | 277344139215 |
| 12 | 277344139215 |
| 13 | 2045466215756535 |