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 | -2 |
| 3 | 1 |
| 4 | 6 |
| 5 | -18 |
| 6 | 8 |
| 7 | 89 |
| 8 | -266 |
| 9 | 62 |
| 10 | 1684 |
| 11 | -4710 |
| 12 | -220 |
| 13 | 35648 |
| 14 | -91236 |
| 15 | -34871 |
| 16 | 803302 |
| 17 | -1856874 |
| 18 | -1448844 |
| 19 | 18809694 |
| 20 | -38816620 |
| 21 | -48910700 |
| 22 | 451491680 |
| 23 | -820626294 |
| 24 | -1522994404 |
| 25 | 11015923292 |
| 26 | -17319046712 |
| 27 | -45512957516 |
| 28 | 271664145264 |
| 29 | -359911736252 |
| 30 | -1327355044924 |