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 | 2 |
| 3 | 3 |
| 4 | 0 |
| 5 | -5 |
| 6 | 0 |
| 7 | 21 |
| 8 | 0 |
| 9 | -153 |
| 10 | 0 |
| 11 | 1705 |
| 12 | 0 |
| 13 | -26949 |
| 14 | 0 |
| 15 | 573405 |
| 16 | 0 |
| 17 | -15802673 |
| 18 | 0 |
| 19 | 547591761 |
| 20 | 0 |
| 21 | -23302711005 |
| 22 | 0 |
| 23 | 1194695479813 |
| 24 | 0 |
| 25 | -72628776062025 |
| 26 | 0 |
| 27 | 5165901157067001 |
| 28 | 0 |
| 29 | -425013158488292213 |
| 30 | 0 |