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 | -6 |
| 2 | 24 |
| 3 | -80 |
| 4 | 234 |
| 5 | -624 |
| 6 | 1552 |
| 7 | -3648 |
| 8 | 8184 |
| 9 | -17654 |
| 10 | 36816 |
| 11 | -74544 |
| 12 | 147056 |
| 13 | -283440 |
| 14 | 535008 |
| 15 | -990912 |
| 16 | 1803882 |
| 17 | -3232224 |
| 18 | 5707624 |
| 19 | -9943536 |
| 20 | 17106960 |
| 21 | -29088352 |
| 22 | 48922320 |
| 23 | -81438528 |
| 24 | 134261584 |
| 25 | -219336630 |
| 26 | 355242288 |