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 | 7 |
| 2 | 21 |
| 3 | 231 |
| 4 | 3003 |
| 5 | 3003 |
| 6 | 51051 |
| 7 | 969969 |
| 8 | 969969 |
| 9 | 22309287 |
| 10 | 111546435 |
| 11 | 334639305 |
| 12 | 9704539845 |
| 13 | 300840735195 |
| 14 | 300840735195 |
| 15 | 300840735195 |
| 16 | 11131107202215 |
| 17 | 11131107202215 |
| 18 | 456375395290815 |
| 19 | 19624141997505045 |
| 20 | 19624141997505045 |