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 | -9 |
| 2 | 99 |
| 3 | -1287 |
| 4 | 19089 |
| 5 | -316305 |
| 6 | 5772195 |
| 7 | -114729615 |
| 8 | 2462398785 |
| 9 | -56674425465 |
| 10 | 1390839617475 |
| 11 | -36219350942775 |
| 12 | 996780497137425 |
| 13 | -28887911103276225 |
| 14 | 878916406742849475 |
| 15 | -27996927397669605375 |