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 | 21 |
| 5 | 146 |
| 6 | 1246 |
| 7 | 13767 |
| 8 | 252509 |
| 9 | 5755625 |
| 10 | 177353720 |
| 11 | 8354131403 |
| 12 | 523250794396 |
| 13 | 44173651472383 |
| 14 | 5428616779817049 |
| 15 | 920678621074132173 |
| 16 | 212277158481925445968 |
| 17 | 69198443091508695982216 |