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 | -4 |
| 3 | -9 |
| 4 | 160 |
| 5 | 1350 |
| 6 | -14904 |
| 7 | -335160 |
| 8 | 1796096 |
| 9 | 125615448 |
| 10 | 204300000 |
| 11 | -64591072920 |
| 12 | -735003528192 |
| 13 | 41673388751280 |
| 14 | 1113912529707264 |
| 15 | -30043364514345000 |
| 16 | -1703374149711298560 |
| 17 | 17822402097051182400 |
| 18 | 2856178489894627203072 |
| 19 | 12394040043610922716800 |
| 20 | -5255899207995216384000000 |