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 | -6 |
| 5 | 2 |
| 6 | 0 |
| 7 | 2 |
| 8 | -1680 |
| 9 | 10082 |
| 10 | 0 |
| 11 | 2 |
| 12 | -665280 |
| 13 | 2 |
| 14 | 0 |
| 15 | 3632428802 |
| 16 | -36843206400 |
| 17 | 2 |
| 18 | 0 |
| 19 | 2 |
| 20 | -670442572800 |
| 21 | 3379030566912002 |
| 22 | 0 |
| 23 | 2 |
| 24 | -71812452903064473600 |
| 25 | 1077167364120207360002 |
| 26 | 0 |
| 27 | 10002268381116211200002 |
| 28 | -3497296636753920000 |
| 29 | 2 |
| 30 | 0 |
| 31 | 2 |