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 | 0 |
| 3 | -2 |
| 4 | 0 |
| 5 | 16 |
| 6 | 0 |
| 7 | -272 |
| 8 | 0 |
| 9 | 7936 |
| 10 | 0 |
| 11 | -353792 |
| 12 | 0 |
| 13 | 22368256 |
| 14 | 0 |
| 15 | -1903757312 |
| 16 | 0 |
| 17 | 209865342976 |
| 18 | 0 |
| 19 | -29088885112832 |
| 20 | 0 |
| 21 | 4951498053124096 |
| 22 | 0 |
| 23 | -1015423886506852352 |
| 24 | 0 |
| 25 | 246921480190207983616 |
| 26 | 0 |
| 27 | -70251601603943959887872 |
| 28 | 0 |
| 29 | 23119184187809597841473536 |
| 30 | 0 |