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 | -420 |
| 2 | -31500 |
| 3 | -4724160 |
| 4 | -1314429900 |
| 5 | -440028142344 |
| 6 | -162555920654400 |
| 7 | -63990327056960640 |
| 8 | -26341675849615282380 |
| 9 | -11210298679649742846180 |
| 10 | -4895195936831699458605912 |
| 11 | -2181913188022929464292248640 |