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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | 0 |
| 5 | 13 |
| 6 | 5 |
| 7 | -336 |
| 8 | -56 |
| 9 | 18593 |
| 10 | -6735 |
| 11 | -1598520 |
| 12 | 1192664 |
| 13 | 205475645 |
| 14 | -255011835 |
| 15 | -36324220856 |
| 16 | 62049925040 |
| 17 | 8519764352097 |
| 18 | -18835422533375 |
| 19 | -2551646722754512 |
| 20 | 6927586371061712 |
| 21 | 951619735931190157 |
| 22 | -3077560879933239899 |
| 23 | -432185107142832520576 |
| 24 | 1624964470900980885432 |