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 | 21 |
| 3 | 286 |
| 4 | 8855 |
| 5 | 501942 |
| 6 | 45057474 |
| 7 | 5843355957 |
| 8 | 1029873432159 |
| 9 | 236236542585120 |
| 10 | 68292983465630781 |
| 11 | 24268885951464043344 |
| 12 | 10392619362579990298763 |
| 13 | 5276256293478688846049120 |