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 | -4 |
| 3 | 39 |
| 4 | -616 |
| 5 | 13505 |
| 6 | -379296 |
| 7 | 12995983 |
| 8 | -525688192 |
| 9 | 24519144609 |
| 10 | -1295527513600 |
| 11 | 76481653648631 |
| 12 | -4989249262503936 |
| 13 | 356408413864589281 |
| 14 | -27670449142629400576 |
| 15 | 2319870547729387929375 |
| 16 | -208886312501433616531456 |
| 17 | 20104397299878424990749377 |