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 | 1 |
| 3 | 6 |
| 4 | 36 |
| 5 | 231 |
| 6 | 1386 |
| 7 | 8496 |
| 8 | 50976 |
| 9 | 306956 |
| 10 | 1842276 |
| 11 | 11060586 |
| 12 | 66363516 |
| 13 | 398229516 |
| 14 | 2389377096 |
| 15 | 14336517456 |
| 16 | 86019146316 |
| 17 | 516116428791 |
| 18 | 3096698572746 |
| 19 | 18580200896796 |
| 20 | 111481205380776 |
| 21 | 668887287816276 |