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 | 2 |
| 2 | 0 |
| 3 | 4 |
| 4 | -6 |
| 5 | 32 |
| 6 | -88 |
| 7 | 376 |
| 8 | -1376 |
| 9 | 5574 |
| 10 | -22232 |
| 11 | 91548 |
| 12 | -378736 |
| 13 | 1589304 |
| 14 | -6719040 |
| 15 | 28647592 |
| 16 | -122933470 |
| 17 | 530755764 |
| 18 | -2303432600 |
| 19 | 10043949684 |
| 20 | -43979901840 |
| 21 | 193309672224 |
| 22 | -852599615912 |
| 23 | 3772221225128 |
| 24 | -16737583019616 |
| 25 | 74461240879386 |