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 | -1 |
| 2 | -4 |
| 3 | 9 |
| 4 | 48 |
| 5 | 100 |
| 6 | -756 |
| 7 | -3479 |
| 8 | -1600 |
| 9 | 24462 |
| 10 | 225900 |
| 11 | 364573 |
| 12 | -643536 |
| 13 | -9251736 |
| 14 | -36989316 |
| 15 | -32397975 |
| 16 | 165039872 |
| 17 | 1725828525 |
| 18 | 5338814652 |
| 19 | 8082713829 |
| 20 | -26321848400 |
| 21 | -233434232766 |
| 22 | -811526778964 |
| 23 | -1731126953532 |
| 24 | 1151302859712 |
| 25 | 23632432765000 |
| 26 | 113461901639788 |
| 27 | 287935019845749 |