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 | 4 |
| 3 | 24 |
| 4 | 206 |
| 5 | 2300 |
| 6 | 31742 |
| 7 | 522466 |
| 8 | 9996478 |
| 9 | 218088504 |
| 10 | 5344652492 |
| 11 | 145386399554 |
| 12 | 4347272984936 |
| 13 | 141737636485588 |
| 14 | 5004538251283846 |
| 15 | 190247639729155110 |
| 16 | 7747479351505166738 |
| 17 | 336492490519027631984 |
| 18 | 15526758954835131888980 |
| 19 | 758548951300064645742034 |