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 | -1 |
| 2 | 3 |
| 3 | -1 |
| 4 | 15 |
| 5 | -3 |
| 6 | 63 |
| 7 | -9 |
| 8 | 135 |
| 9 | -15 |
| 10 | 99 |
| 11 | -9 |
| 12 | 12285 |
| 13 | -945 |
| 14 | 405 |
| 15 | -27 |
| 16 | 6885 |
| 17 | -405 |
| 18 | 161595 |
| 19 | -8505 |
| 20 | 1403325 |
| 21 | -66825 |
| 22 | 419175 |
| 23 | -18225 |
| 24 | 24877125 |
| 25 | -995085 |
| 26 | 229635 |
| 27 | -8505 |
| 28 | 528525 |
| 29 | -18225 |
| 30 | 26101845 |
| 31 | -841995 |
| 32 | 214708725 |
| 33 | -6506325 |
| 34 | 1148175 |
| 35 | -32805 |
| 36 | 31479513975 |
| 37 | -850797675 |