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 | 0 |
| 3 | 3 |
| 4 | 3 |
| 5 | -51 |
| 6 | -75 |
| 7 | 2253 |
| 8 | 1491 |
| 9 | -192651 |
| 10 | -187275 |
| 11 | 27071553 |
| 12 | 278562603 |
| 13 | -5649998901 |
| 14 | -36187521825 |
| 15 | 1637735135403 |
| 16 | 25110810761403 |
| 17 | -628821435060051 |
| 18 | -1403714584628625 |
| 19 | 308746181051792553 |
| 20 | 6294348598730683953 |
| 21 | -188636884672112018601 |
| 22 | -2161564244998001617125 |