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 | 1 |
| 3 | -2 |
| 4 | -1 |
| 5 | 10 |
| 6 | -24 |
| 7 | 16 |
| 8 | 1 |
| 9 | -42 |
| 10 | 504 |
| 11 | -2640 |
| 12 | 7040 |
| 13 | -9984 |
| 14 | 7168 |
| 15 | -2048 |
| 16 | -1 |
| 17 | 170 |
| 18 | -8568 |
| 19 | 201552 |
| 20 | -2687360 |
| 21 | 22573824 |
| 22 | -127339520 |
| 23 | 502081536 |
| 24 | -1417641984 |
| 25 | 2901606400 |
| 26 | -4310958080 |
| 27 | 4600627200 |
| 28 | -3435134976 |
| 29 | 1702887424 |
| 30 | -503316480 |
| 31 | 67108864 |