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 | -2 |
| 4 | -16 |
| 5 | -24 |
| 6 | 64 |
| 7 | -720 |
| 8 | -23808 |
| 9 | -35840 |
| 10 | 282368 |
| 11 | -3628800 |
| 12 | -75458560 |
| 13 | -479001600 |
| 14 | 5315078144 |
| 15 | -82614884352 |
| 16 | -8601835798528 |
| 17 | -20922789888000 |
| 18 | 321288633450496 |
| 19 | -6402373705728000 |
| 20 | -309168395474436096 |
| 21 | -2379913632645120000 |
| 22 | 46441359567137275904 |