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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 32 |
| 5 | 135 |
| 6 | 709 |
| 7 | 4637 |
| 8 | 38374 |
| 9 | 391473 |
| 10 | 4764778 |
| 11 | 66913591 |
| 12 | 1056886475 |
| 13 | 18446472265 |
| 14 | 351482430368 |
| 15 | 7247888726269 |
| 16 | 160671989129665 |
| 17 | 3808499268504548 |
| 18 | 96094161981827499 |
| 19 | 2570930535917564366 |
| 20 | 72688753062897675445 |