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 | 0 |
| 4 | 0 |
| 5 | -1 |
| 6 | -1 |
| 7 | -1 |
| 8 | -1 |
| 9 | -1 |
| 10 | 125 |
| 11 | 461 |
| 12 | 1253 |
| 13 | 3002 |
| 14 | 6720 |
| 15 | -111684 |
| 16 | -978758 |
| 17 | -5246983 |
| 18 | -22948029 |
| 19 | -89534309 |
| 20 | 164027151 |
| 21 | 5722510249 |
| 22 | 55413784239 |
| 23 | 393256686307 |
| 24 | 2377996545081 |
| 25 | 7807749195198 |
| 26 | -46231762188586 |
| 27 | -1125536160278906 |
| 28 | -12849721017510166 |