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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | -4 |
| 5 | 29 |
| 6 | -174 |
| 7 | 1583 |
| 8 | -13168 |
| 9 | 144153 |
| 10 | -1485330 |
| 11 | 20127867 |
| 12 | -253341144 |
| 13 | 3978820221 |
| 14 | -57986205900 |
| 15 | 1057400360235 |
| 16 | -18016221644544 |
| 17 | 370244721585681 |
| 18 | -6993826454599146 |
| 19 | 162968423791332339 |
| 20 | -3490951922268853320 |
| 21 | 88052648301403014789 |
| 22 | -2075060448716599488276 |