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 | 3 |
| 3 | 18 |
| 4 | 163 |
| 5 | 1950 |
| 6 | 28821 |
| 7 | 505876 |
| 8 | 10270569 |
| 9 | 236644092 |
| 10 | 6098971555 |
| 11 | 173823708696 |
| 12 | 5427760272507 |
| 13 | 184267682837992 |
| 14 | 6757353631762293 |
| 15 | 266191329601854000 |
| 16 | 11210291102456374801 |
| 17 | 502602430218071545104 |
| 18 | 23900770928782913595651 |
| 19 | 1201581698963550283673632 |