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 | 4 |
| 2 | 32 |
| 3 | 212 |
| 4 | 1504 |
| 5 | 10848 |
| 6 | 79696 |
| 7 | 596160 |
| 8 | 4520000 |
| 9 | 34673940 |
| 10 | 268538048 |
| 11 | 2096374656 |
| 12 | 16475970896 |
| 13 | 130234435648 |
| 14 | 1034568731408 |
| 15 | 8254368150320 |
| 16 | 66112337392256 |
| 17 | 531345216883584 |
| 18 | 4283682906179728 |
| 19 | 34632004320564416 |