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) |
|---|---|
| 3 | 1 |
| 4 | 10 |
| 5 | 73 |
| 6 | 425 |
| 7 | 1561 |
| 8 | -2856 |
| 9 | -73520 |
| 10 | 380160 |
| 11 | 15376416 |
| 12 | -117209664 |
| 13 | -7506967104 |
| 14 | 72162155520 |
| 15 | 7045087741056 |
| 16 | -80246202992640 |
| 17 | -11448278791372800 |
| 18 | 149576169325363200 |
| 19 | 30017051616972275712 |
| 20 | -440857664887810867200 |