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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | -3 |
| 7 | 6 |
| 8 | -9 |
| 9 | 6 |
| 10 | 27 |
| 11 | -169 |
| 12 | 645 |
| 13 | -1995 |
| 14 | 5122 |
| 15 | -9570 |
| 16 | 1242 |
| 17 | 109739 |
| 18 | -756648 |
| 19 | 3733128 |
| 20 | -15527337 |
| 21 | 55626585 |
| 22 | -161247102 |
| 23 | 260402511 |
| 24 | 1028417064 |
| 25 | -14243992155 |
| 26 | 102551438561 |
| 27 | -595149283191 |
| 28 | 3010031905815 |
| 29 | -13336771020834 |
| 30 | 48891499316016 |
| 31 | -111677138548476 |