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 | 0 |
| 3 | -1 |
| 4 | 2 |
| 5 | 6 |
| 6 | -11 |
| 7 | -35 |
| 8 | 73 |
| 9 | 232 |
| 10 | -516 |
| 11 | -1646 |
| 12 | 3825 |
| 13 | 12239 |
| 14 | -29344 |
| 15 | -94137 |
| 16 | 231050 |
| 17 | 742825 |
| 18 | -1856679 |
| 19 | -5980056 |
| 20 | 15166101 |
| 21 | 48922556 |
| 22 | -125557710 |
| 23 | -405553786 |
| 24 | 1051197507 |
| 25 | 3399234751 |