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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 30 |
| 5 | 504 |
| 6 | 1978 |
| 7 | 714840 |
| 8 | 500421564 |
| 9 | 4855562127780 |
| 10 | 1169461626163992 |
| 11 | 112848995546998874467920 |
| 12 | 7363180440 |