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 | 6 |
| 2 | 252 |
| 3 | 272 |
| 4 | 858 |
| 5 | 2772 |
| 6 | 4004 |
| 7 | 6006 |
| 8 | 289982 |
| 9 | 2370732 |
| 10 | 2629262 |
| 11 | 6039306 |
| 12 | 27999972 |
| 13 | 28233282 |
| 14 | 2704884072 |
| 15 | 20278187202 |
| 16 | 20591819502 |
| 17 | 2592587852952 |
| 18 | 2936231326392 |
| 19 | 21809166190812 |
| 20 | 27237788773272 |
| 21 | 229145919541922 |