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 | -1 |
| 3 | 4 |
| 4 | 1 |
| 5 | -21 |
| 6 | 14 |
| 7 | 111 |
| 8 | -195 |
| 9 | -529 |
| 10 | 1837 |
| 11 | 1792 |
| 12 | -14772 |
| 13 | 2300 |
| 14 | 105431 |
| 15 | -126697 |
| 16 | -657427 |
| 17 | 1650427 |
| 18 | 3285795 |
| 19 | -16211352 |
| 20 | -8308737 |
| 21 | 135770125 |
| 22 | -79748628 |
| 23 | -990431659 |
| 24 | 1700106664 |
| 25 | 6098396204 |
| 26 | -20258923714 |
| 27 | -27342511804 |
| 28 | 193913175511 |
| 29 | 12018867589 |