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 | -2 |
| 4 | 0 |
| 5 | 0 |
| 6 | 40 |
| 7 | -2 |
| 8 | 0 |
| 9 | -2240 |
| 10 | 480 |
| 11 | -2 |
| 12 | 246400 |
| 13 | -137280 |
| 14 | 8320 |
| 15 | -44844802 |
| 16 | 51251200 |
| 17 | -10325120 |
| 18 | 12197916160 |
| 19 | -24831206402 |
| 20 | 11394406400 |
| 21 | -4636033573760 |
| 22 | 15296025241600 |
| 23 | -13230894476802 |
| 24 | 2348235343872000 |