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 | 1 |
| 5 | 0 |
| 6 | -5 |
| 7 | 20 |
| 8 | -55 |
| 9 | 125 |
| 10 | -246 |
| 11 | 406 |
| 12 | -461 |
| 13 | -144 |
| 14 | 3004 |
| 15 | -11978 |
| 16 | 35113 |
| 17 | -86293 |
| 18 | 181663 |
| 19 | -314603 |
| 20 | 365922 |
| 21 | 150023 |
| 22 | -2696308 |
| 23 | 10969573 |
| 24 | -32970453 |
| 25 | 82976409 |
| 26 | -178372934 |
| 27 | 314133884 |
| 28 | -367436684 |
| 29 | -179661091 |
| 30 | 2923282216 |
| 31 | -11972239216 |
| 32 | 36369188841 |
| 33 | -92517132841 |