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 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 121 |
| 6 | 721 |
| 7 | 2521 |
| 8 | 6721 |
| 9 | 378001 |
| 10 | 7287841 |
| 11 | 59930641 |
| 12 | 319429441 |
| 13 | 7524471241 |
| 14 | 353072319601 |
| 15 | 5897248517161 |
| 16 | 55827317669761 |
| 17 | 726274560953761 |
| 18 | 53139878190826561 |
| 19 | 1650487849152976801 |
| 20 | 25981849479032542081 |
| 21 | 317292238756098973081 |