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 | -2 |
| 2 | -60 |
| 3 | -120 |
| 4 | -5040 |
| 5 | -10080 |
| 6 | -302400 |
| 7 | -604800 |
| 8 | -39916800 |
| 9 | -79833600 |
| 10 | -217945728000 |
| 11 | -435891456000 |
| 12 | -2615348736000 |
| 13 | -5230697472000 |
| 14 | -2667655710720000 |
| 15 | -5335311421440000 |
| 16 | -4257578514309120000 |
| 17 | -8515157028618240000 |
| 18 | -2810001819444019200000 |