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 | 9 |
| 4 | 43 |
| 5 | 213 |
| 6 | 1507 |
| 7 | 12537 |
| 8 | 114325 |
| 9 | 1144221 |
| 10 | 12512373 |
| 11 | 148351881 |
| 12 | 1892798733 |
| 13 | 25816700309 |
| 14 | 374406371121 |
| 15 | 5748436717505 |
| 16 | 93098093268755 |
| 17 | 1585364420710205 |
| 18 | 28305454044441843 |
| 19 | 528500175862180033 |
| 20 | 10295596472841577779 |