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 | -89 |
| 4 | 377 |
| 5 | -1597 |
| 6 | 6765 |
| 7 | -28657 |
| 8 | 121393 |
| 9 | -514229 |
| 10 | 2178309 |
| 11 | -9227465 |
| 12 | 39088169 |
| 13 | -165580141 |
| 14 | 701408733 |
| 15 | -2971215073 |
| 16 | 12586269025 |
| 17 | -53316291173 |
| 18 | 225851433717 |
| 19 | -956722026041 |
| 20 | 4052739537881 |
| 21 | -17167680177565 |
| 22 | 72723460248141 |
| 23 | -308061521170129 |
| 24 | 1304969544928657 |