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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | -1 |
| 4 | 4 |
| 5 | -19 |
| 6 | 44 |
| 7 | -659 |
| 8 | 8128 |
| 9 | -18775 |
| 10 | 67664 |
| 11 | -3578279 |
| 12 | 7629568 |
| 13 | -476298835 |
| 14 | 505198784 |
| 15 | 25626362581 |
| 16 | 4286437900288 |
| 17 | -20903398375855 |
| 18 | -118410655250176 |
| 19 | -6399968826052559 |
| 20 | -33100680116191232 |
| 21 | 1010700510694925525 |
| 22 | 706348515575880704 |
| 23 | -1123931378903214542099 |