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 | 1 |
| 3 | 23 |
| 4 | 199 |
| 5 | 2297 |
| 6 | 30013 |
| 7 | 510491 |
| 8 | 9699667 |
| 9 | 223092841 |
| 10 | 6469693199 |
| 11 | 200560490093 |
| 12 | 7420738134769 |
| 13 | 304250263527167 |
| 14 | 13082761331669983 |
| 15 | 614889782588491357 |
| 16 | 32589158477190044671 |
| 17 | 1922760350154212639009 |