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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 2 |
| 5 | -2 |
| 6 | 6 |
| 7 | 0 |
| 8 | 16 |
| 9 | -16 |
| 10 | 24 |
| 11 | 24 |
| 12 | -48 |
| 13 | 144 |
| 14 | -120 |
| 15 | 120 |
| 16 | 0 |
| 17 | 432 |
| 18 | -864 |
| 19 | 1392 |
| 20 | -960 |
| 21 | 720 |
| 22 | 720 |
| 23 | -2160 |
| 24 | 8208 |
| 25 | -12816 |
| 26 | 14448 |
| 27 | -8400 |
| 28 | 5040 |
| 29 | 0 |
| 30 | 23040 |
| 31 | -69120 |
| 32 | 149760 |
| 33 | -184320 |
| 34 | 161280 |
| 35 | -80640 |
| 36 | 40320 |
| 37 | 40320 |
| 38 | -161280 |
| 39 | 760320 |
| 40 | -1716480 |
| 41 | 2684160 |
| 42 | -2695680 |