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 | 0 |
| 1 | 1 |
| 2 | 9 |
| 3 | 66 |
| 4 | 490 |
| 5 | 3915 |
| 6 | 34251 |
| 7 | 328804 |
| 8 | 3452436 |
| 9 | 39456405 |
| 10 | 488273005 |
| 11 | 6510306726 |
| 12 | 93097386174 |
| 13 | 1421850988831 |
| 14 | 23105078568495 |
| 15 | 398118276872520 |
| 16 | 7251440043035176 |
| 17 | 139227648826275369 |
| 18 | 2810658160680434001 |
| 19 | 59519819873232720010 |
| 20 | 1319356007189991960210 |