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 | 4 |
| 1 | -1 |
| 2 | 9 |
| 3 | -16 |
| 4 | 49 |
| 5 | -121 |
| 6 | 324 |
| 7 | -841 |
| 8 | 2209 |
| 9 | -5776 |
| 10 | 15129 |
| 11 | -39601 |
| 12 | 103684 |
| 13 | -271441 |
| 14 | 710649 |
| 15 | -1860496 |
| 16 | 4870849 |
| 17 | -12752041 |
| 18 | 33385284 |
| 19 | -87403801 |
| 20 | 228826129 |
| 21 | -599074576 |
| 22 | 1568397609 |
| 23 | -4106118241 |
| 24 | 10749957124 |
| 25 | -28143753121 |
| 26 | 73681302249 |
| 27 | -192900153616 |
| 28 | 505019158609 |
| 29 | -1322157322201 |