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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 9 |
| 4 | 99 |
| 5 | 1301 |
| 6 | 20581 |
| 7 | 376891 |
| 8 | 7914216 |
| 9 | 186905206 |
| 10 | 4915451602 |
| 11 | 142368695176 |
| 12 | 4506118905870 |
| 13 | 154720069309364 |
| 14 | 5729167232515112 |
| 15 | 227585086051159866 |
| 16 | 9654819212943764500 |
| 17 | 435659280972794395356 |
| 18 | 20836049921760968809231 |
| 19 | 1052864549462731148832219 |