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 | 0 |
| 3 | 0 |
| 4 | -2 |
| 5 | 0 |
| 6 | 0 |
| 7 | -16 |
| 8 | 18 |
| 9 | 0 |
| 10 | -168 |
| 11 | 384 |
| 12 | -314 |
| 13 | -1632 |
| 14 | 6264 |
| 15 | -9744 |
| 16 | -10014 |
| 17 | 86976 |
| 18 | -205344 |
| 19 | 80176 |
| 20 | 1009338 |
| 21 | -3579568 |
| 22 | 4575296 |
| 23 | 8301024 |
| 24 | -54012882 |
| 25 | 112640896 |
| 26 | -5164464 |
| 27 | -694845120 |
| 28 | 2160781086 |