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 | -5 |
| 2 | -20 |
| 3 | 370 |
| 4 | 6880 |
| 5 | -84080 |
| 6 | -4764320 |
| 7 | 13835920 |
| 8 | 5296238080 |
| 9 | 57709630720 |
| 10 | -8215749893120 |
| 11 | -267412364065280 |
| 12 | 15638020342497280 |
| 13 | 1127961849051627520 |
| 14 | -29166891598121553920 |
| 15 | -5249813654826672404480 |