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 | -1 |
| 2 | -6 |
| 3 | -22 |
| 4 | 120 |
| 5 | 3464 |
| 6 | 30864 |
| 7 | -189232 |
| 8 | -11564160 |
| 9 | -173474176 |
| 10 | 923222784 |
| 11 | 112587838208 |
| 12 | 2509094415360 |
| 13 | -7947533372416 |
| 14 | -2393798607108096 |
| 15 | -74042111038461952 |
| 16 | -8461127118520320 |
| 17 | 94056121376877215744 |