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 | 7 |
| 2 | -35 |
| 3 | 259 |
| 4 | -1799 |
| 5 | 12607 |
| 6 | -88235 |
| 7 | 617659 |
| 8 | -4323599 |
| 9 | 30265207 |
| 10 | -211856435 |
| 11 | 1482995059 |
| 12 | -10380965399 |
| 13 | 72666757807 |
| 14 | -508667304635 |
| 15 | 3560671132459 |
| 16 | -24924697927199 |
| 17 | 174472885490407 |
| 18 | -1221310198432835 |
| 19 | 8549171389029859 |