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 | -3 |
| 3 | 8 |
| 4 | 31 |
| 5 | -156 |
| 6 | -937 |
| 7 | 6558 |
| 8 | 52463 |
| 9 | -472168 |
| 10 | -4721681 |
| 11 | 51938490 |
| 12 | 623261879 |
| 13 | -8102404428 |
| 14 | -113433661993 |
| 15 | 1701504929894 |
| 16 | 27224078878303 |
| 17 | -462809340931152 |
| 18 | -8330568136760737 |
| 19 | 158280794598454002 |