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 | -2 |
| 3 | 10 |
| 4 | -69 |
| 5 | 568 |
| 6 | -5250 |
| 7 | 52792 |
| 8 | -566830 |
| 9 | 6420640 |
| 10 | -76095972 |
| 11 | 938077528 |
| 12 | -11975951312 |
| 13 | 157808048792 |
| 14 | -2140767942096 |
| 15 | 29835756120952 |
| 16 | -426490803168368 |
| 17 | 6244476409802008 |
| 18 | -93541594534237356 |
| 19 | 1432261132629484052 |
| 20 | -22397290780155132728 |