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 | 3 |
| 2 | 0 |
| 3 | 99 |
| 4 | -270 |
| 5 | 2430 |
| 6 | -10287 |
| 7 | 105462 |
| 8 | -750141 |
| 9 | 5702481 |
| 10 | -42623901 |
| 11 | 347424633 |
| 12 | -2779077762 |
| 13 | 22353287634 |
| 14 | -181730796723 |
| 15 | 1493711042589 |
| 16 | -12321529794261 |
| 17 | 102125312638713 |
| 18 | -850797139405887 |
| 19 | 7120067746384863 |
| 20 | -59800770201017934 |
| 21 | 503922807927384129 |
| 22 | -4259721779079782751 |