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 | 0 |
| 3 | -6 |
| 4 | 16 |
| 5 | -18 |
| 6 | 48 |
| 7 | -94 |
| 8 | 208 |
| 9 | -426 |
| 10 | 752 |
| 11 | -1646 |
| 12 | 3360 |
| 13 | -6578 |
| 14 | 13056 |
| 15 | -26358 |
| 16 | 53456 |
| 17 | -105890 |
| 18 | 211392 |
| 19 | -424366 |
| 20 | 850544 |
| 21 | -1699290 |
| 22 | 3393136 |
| 23 | -6795646 |
| 24 | 13601184 |
| 25 | -27188130 |
| 26 | 54358000 |
| 27 | -108752870 |
| 28 | 217552976 |
| 29 | -435033618 |
| 30 | 869999584 |
| 31 | -1740145118 |
| 32 | 3480497584 |