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 | 3 |
| 2 | 0 |
| 3 | 18 |
| 4 | -81 |
| 5 | 567 |
| 6 | -3888 |
| 7 | 28188 |
| 8 | -209952 |
| 9 | 1600398 |
| 10 | -12417786 |
| 11 | 97750152 |
| 12 | -778646358 |
| 13 | 6264403434 |
| 14 | -50826308652 |
| 15 | 415388851020 |
| 16 | -3416382463113 |
| 17 | 28254462711543 |
| 18 | -234821716366914 |
| 19 | 1960141044056202 |
| 20 | -16426217919609621 |
| 21 | 138140613244558143 |
| 22 | -1165452696039219804 |