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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | -7 |
| 5 | -7 |
| 6 | -7 |
| 7 | 57 |
| 8 | 57 |
| 9 | 57 |
| 10 | -455 |
| 11 | -455 |
| 12 | -455 |
| 13 | 3641 |
| 14 | 3641 |
| 15 | 3641 |
| 16 | -29127 |
| 17 | -29127 |
| 18 | -29127 |
| 19 | 233017 |
| 20 | 233017 |
| 21 | 233017 |
| 22 | -1864135 |
| 23 | -1864135 |
| 24 | -1864135 |
| 25 | 14913081 |
| 26 | 14913081 |
| 27 | 14913081 |
| 28 | -119304647 |
| 29 | -119304647 |
| 30 | -119304647 |