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 | 0 |
| 2 | 1 |
| 3 | -3 |
| 4 | 19 |
| 5 | -223 |
| 6 | 5024 |
| 7 | -221357 |
| 8 | 19276981 |
| 9 | -3337101203 |
| 10 | 1151813749025 |
| 11 | -793860037771900 |
| 12 | 1093434531716214447 |
| 13 | -3010922236710802264555 |
| 14 | 16578683647583849207539977 |
| 15 | -182552322688781602767983229935 |