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 | -4 |
| 4 | -2 |
| 5 | -4 |
| 6 | 2 |
| 7 | -20 |
| 8 | 86 |
| 9 | -532 |
| 10 | 3706 |
| 11 | -29668 |
| 12 | 266990 |
| 13 | -2669924 |
| 14 | 29369138 |
| 15 | -352429684 |
| 16 | 4581585862 |
| 17 | -64142202100 |
| 18 | 962133031466 |
| 19 | -15394128503492 |
| 20 | 261700184559326 |
| 21 | -4710603322067908 |
| 22 | 89501463119290210 |
| 23 | -1790029262385804244 |