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 | 0 |
| 3 | -6 |
| 4 | -12 |
| 5 | -20 |
| 6 | 330 |
| 7 | 2478 |
| 8 | 11704 |
| 9 | -15192 |
| 10 | -751050 |
| 11 | -7817150 |
| 12 | -38408172 |
| 13 | 151402524 |
| 14 | 5793891922 |
| 15 | 69046056870 |
| 16 | 393083614320 |
| 17 | -2517944476592 |
| 18 | -98819987200146 |
| 19 | -1384209703077750 |
| 20 | -9376308260215220 |
| 21 | 67288368700200900 |
| 22 | 3186749671049174538 |