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 | -3 |
| 3 | 12 |
| 4 | -57 |
| 5 | 304 |
| 6 | -1757 |
| 7 | 10746 |
| 8 | -68450 |
| 9 | 449274 |
| 10 | -3016645 |
| 11 | 20618317 |
| 12 | -142946735 |
| 13 | 1002722249 |
| 14 | -7103064540 |
| 15 | 50738237140 |
| 16 | -365049115546 |
| 17 | 2642981328372 |
| 18 | -19241453032254 |
| 19 | 140770867457795 |
| 20 | -1034409857616986 |
| 21 | 7631075823632553 |
| 22 | -56497364856268721 |
| 23 | 419641611512419630 |
| 24 | -3126180409889288924 |