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 | 6 |
| 3 | -180 |
| 4 | 8640 |
| 5 | -498960 |
| 6 | 31434480 |
| 7 | -2055943296 |
| 8 | 135216506304 |
| 9 | -8720972739072 |
| 10 | 538646016002688 |
| 11 | -31024094144060160 |
| 12 | 1609593032459782656 |
| 13 | -71392972690228672512 |
| 14 | 2461961564459510280192 |
| 15 | -51302015299696881770496 |
| 16 | -415041229811424576835584 |