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 | -1 |
| 2 | 1 |
| 3 | -1 |
| 4 | 0 |
| 5 | 4 |
| 6 | -14 |
| 7 | 34 |
| 8 | -65 |
| 9 | 89 |
| 10 | -29 |
| 11 | -331 |
| 12 | 1464 |
| 13 | -4148 |
| 14 | 9010 |
| 15 | -14366 |
| 16 | 9761 |
| 17 | 38895 |
| 18 | -215015 |
| 19 | 674423 |
| 20 | -1594973 |
| 21 | 2829973 |
| 22 | -2732465 |
| 23 | -4812567 |
| 24 | 36116257 |
| 25 | -124617681 |
| 26 | 316617081 |
| 27 | -611942761 |
| 28 | 735416371 |
| 29 | 488457845 |
| 30 | -6451021289 |
| 31 | 24658985649 |
| 32 | -66990721867 |
| 33 | 139346533259 |