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 | 1 |
| 3 | -2 |
| 4 | 2 |
| 5 | -19 |
| 6 | 39 |
| 7 | -257 |
| 8 | 1113 |
| 9 | -6829 |
| 10 | 42399 |
| 11 | -299550 |
| 12 | 2281531 |
| 13 | -18901042 |
| 14 | 168402645 |
| 15 | -1608304966 |
| 16 | 16381456532 |
| 17 | -177291076953 |
| 18 | 2031597803009 |
| 19 | -24573784682206 |
| 20 | 312883002507064 |
| 21 | -4182938253898882 |
| 22 | 58584703430964506 |
| 23 | -857812167322107132 |
| 24 | 13106404407407087063 |