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 | 0 |
| 2 | 0 |
| 3 | -1 |
| 4 | -6 |
| 5 | -25 |
| 6 | -80 |
| 7 | -91 |
| 8 | 1694 |
| 9 | 23155 |
| 10 | 206340 |
| 11 | 1442969 |
| 12 | 6928394 |
| 13 | -6507865 |
| 14 | -752409840 |
| 15 | -12953182971 |
| 16 | -160186016906 |
| 17 | -1548849362085 |
| 18 | -9789241693220 |
| 19 | 28359195353489 |
| 20 | 2378650585685794 |
| 21 | 52832659521004495 |
| 22 | 855581150441210600 |
| 23 | 10878338100191146749 |