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 | -4 |
| 3 | 20 |
| 4 | -224 |
| 5 | 3392 |
| 6 | -67232 |
| 7 | 1629728 |
| 8 | -46799104 |
| 9 | 1552143104 |
| 10 | -58386807296 |
| 11 | 2455954797056 |
| 12 | -114222622662656 |
| 13 | 5819845970653184 |
| 14 | -322384671892123648 |
| 15 | 19290013218140254208 |
| 16 | -1239886482366130946048 |
| 17 | 85200320552417960394752 |