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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | -9 |
| 5 | 44 |
| 6 | -165 |
| 7 | 594 |
| 8 | -2037 |
| 9 | 6824 |
| 10 | -22437 |
| 11 | 72830 |
| 12 | -234047 |
| 13 | 746316 |
| 14 | -2364947 |
| 15 | 7455798 |
| 16 | -23405085 |
| 17 | 73207728 |
| 18 | -228275949 |
| 19 | 709906518 |
| 20 | -2202557691 |
| 21 | 6819616020 |
| 22 | -21076580511 |
| 23 | 65032888998 |
| 24 | -200369138571 |
| 25 | 616531573224 |
| 26 | -1894784517675 |
| 27 | 5816886949874 |