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 | 1 |
| 3 | 5 |
| 4 | -91 |
| 5 | -85 |
| 6 | 3751 |
| 7 | 3185 |
| 8 | -138811 |
| 9 | -207913 |
| 10 | 25143755 |
| 11 | 20824925 |
| 12 | -125284471321 |
| 13 | -2961364861 |
| 14 | 45706820257 |
| 15 | 567040692425 |
| 16 | -850303535348267 |
| 17 | -140642298254929 |
| 18 | 371258049560506117 |
| 19 | 43861384856264885 |
| 20 | -53200355263894712681 |
| 21 | -16798626454194814117 |