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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | -2 |
| 4 | 13 |
| 5 | -145 |
| 6 | 2328 |
| 7 | -49784 |
| 8 | 1358965 |
| 9 | -46076544 |
| 10 | 1902202515 |
| 11 | -94104681660 |
| 12 | 5503867176832 |
| 13 | -376096374571125 |
| 14 | 29714871818774044 |
| 15 | -2689473418781240320 |
| 16 | 276562260699626541509 |
| 17 | -32073434441440654231749 |
| 18 | 4167256779254698145624064 |
| 19 | -603002974281204853457239860 |