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 | -8 |
| 5 | -16 |
| 6 | 16 |
| 7 | 195 |
| 8 | 491 |
| 9 | -317 |
| 10 | -6293 |
| 11 | -18608 |
| 12 | 4610 |
| 13 | 230385 |
| 14 | 780625 |
| 15 | 107615 |
| 16 | -9028280 |
| 17 | -34695607 |
| 18 | -17401607 |
| 19 | 367885509 |
| 20 | 1598468196 |
| 21 | 1350497961 |
| 22 | -15317000747 |
| 23 | -75391402496 |
| 24 | -88375867528 |
| 25 | 643505487144 |
| 26 | 3611942077216 |
| 27 | 5376931884971 |