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 | -4 |
| 5 | -4 |
| 6 | -48 |
| 7 | -336 |
| 8 | -2928 |
| 9 | -28144 |
| 10 | -298528 |
| 11 | -3454432 |
| 12 | -43286528 |
| 13 | -583835648 |
| 14 | -8433987584 |
| 15 | -129941213184 |
| 16 | -2127349165824 |
| 17 | -36889047574272 |
| 18 | -675548628690432 |
| 19 | -13030733384956416 |
| 20 | -264111424634864640 |