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 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 69 |
| 5 | 60 |
| 6 | 4500 |
| 7 | 104580 |
| 8 | 186795 |
| 9 | 13497435 |
| 10 | 442245825 |
| 11 | 13003053525 |
| 12 | 64585694250 |
| 13 | 3576632909850 |
| 14 | 147580842959550 |
| 15 | 5708173568847750 |
| 16 | 27904470362393625 |
| 17 | 2292043480058957625 |
| 18 | 126842184377462428875 |
| 19 | 6371504674680470700375 |
| 20 | 312265748715684068930625 |