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 | 0 |
| 2 | -3 |
| 3 | -9 |
| 4 | 0 |
| 5 | 189 |
| 6 | 1377 |
| 7 | 4374 |
| 8 | -26001 |
| 9 | -560601 |
| 10 | -4999482 |
| 11 | -18631053 |
| 12 | 235966365 |
| 13 | 5966310960 |
| 14 | 71037580689 |
| 15 | 407585191059 |
| 16 | -3965310883512 |
| 17 | -157871090202975 |
| 18 | -2631946996862451 |
| 19 | -24922384546473810 |
| 20 | 45577755305571339 |
| 21 | 7795795206234609027 |
| 22 | 192159735553383097014 |