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 | 5 |
| 3 | 6 |
| 4 | 9 |
| 5 | 20 |
| 6 | 75 |
| 7 | 414 |
| 8 | 2849 |
| 9 | 22728 |
| 10 | 204471 |
| 11 | 2044610 |
| 12 | 22490589 |
| 13 | 269886924 |
| 14 | 3508529843 |
| 15 | 49119417606 |
| 16 | 736791263865 |
| 17 | 11788660221584 |
| 18 | 200407223766639 |
| 19 | 3607330027799178 |
| 20 | 68539270528184021 |
| 21 | 1370785410563680020 |