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 | -4 |
| 3 | 24 |
| 4 | -200 |
| 5 | 2080 |
| 6 | -25932 |
| 7 | 377216 |
| 8 | -6271120 |
| 9 | 117287424 |
| 10 | -2437334420 |
| 11 | 55714920448 |
| 12 | -1389365372760 |
| 13 | 37533886128128 |
| 14 | -1091981490075868 |
| 15 | 34038486791454720 |
| 16 | -1131758947520249120 |
| 17 | 39982188936149204992 |
| 18 | -1495556350390047594276 |
| 19 | 59050025742595595436032 |