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 | 2 |
| 2 | 1 |
| 3 | 2 |
| 4 | 0 |
| 5 | 4 |
| 6 | -5 |
| 7 | 16 |
| 8 | -35 |
| 9 | 92 |
| 10 | -231 |
| 11 | 604 |
| 12 | -1584 |
| 13 | 4214 |
| 14 | -11297 |
| 15 | 30538 |
| 16 | -83096 |
| 17 | 227476 |
| 18 | -625991 |
| 19 | 1730788 |
| 20 | -4805594 |
| 21 | 13393690 |
| 22 | -37458329 |
| 23 | 105089230 |
| 24 | -295673993 |
| 25 | 834086422 |
| 26 | -2358641375 |
| 27 | 6684761126 |
| 28 | -18985057350 |
| 29 | 54022715452 |
| 30 | -154000562757 |
| 31 | 439742222072 |