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) |
|---|---|
| 1 | 1 |
| 2 | -2 |
| 3 | 8 |
| 4 | -48 |
| 5 | 386 |
| 6 | -3905 |
| 7 | 47701 |
| 8 | -683592 |
| 9 | 11250291 |
| 10 | -209168071 |
| 11 | 4336482905 |
| 12 | -99197868847 |
| 13 | 2481962140797 |
| 14 | -67426166949102 |
| 15 | 1976463051528507 |
| 16 | -62178381389729317 |
| 17 | 2089532143617395264 |
| 18 | -74702625442877063902 |
| 19 | 2830904065389397804534 |
| 20 | -113348477836878447492630 |