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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 1 |
| 4 | -4 |
| 5 | 9 |
| 6 | 110 |
| 7 | -279 |
| 8 | -4520 |
| 9 | 17265 |
| 10 | 322618 |
| 11 | -1638031 |
| 12 | -35226860 |
| 13 | 223578809 |
| 14 | 5463436134 |
| 15 | -41639195623 |
| 16 | -1142009233872 |
| 17 | 10162622387809 |
| 18 | 309463272791538 |
| 19 | -3149754003442847 |
| 20 | -105510576441518164 |
| 21 | 1208991988527548137 |
| 22 | 44200537412519181278 |
| 23 | -563099647603189449783 |