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 | 2 |
| 2 | 6 |
| 3 | 28 |
| 4 | 244 |
| 5 | 2544 |
| 6 | 35600 |
| 7 | 659632 |
| 8 | 15106128 |
| 9 | 425802176 |
| 10 | 14409526080 |
| 11 | 577386122880 |