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 | 5 |
| 2 | 21 |
| 3 | 715 |
| 4 | -162877 |
| 5 | 19840275 |
| 6 | -7176079695 |
| 7 | 1829885835675 |
| 8 | -5009184735027165 |
| 9 | 2216222559226679575 |
| 10 | -2463196751104762933637 |
| 11 | 1679951011110471133453965 |
| 12 | -5519118103058048675551057049 |
| 13 | 5373485053345792589762994345215 |
| 14 | -12239617587594386225052760043303511 |