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 | 0 |
| 4 | -1 |
| 5 | -1 |
| 6 | -1 |
| 7 | 1 |
| 8 | 31 |
| 9 | 1 |
| 10 | -2951 |
| 11 | -1 |
| 12 | 181 |
| 13 | 2417 |
| 14 | 58913 |
| 15 | -5699 |
| 16 | -52635599 |
| 17 | -19993 |
| 18 | 1126610929 |
| 19 | 3631 |
| 20 | 27069353 |
| 21 | -6050353 |
| 22 | -118802490419 |
| 23 | 47438 |
| 24 | 11162375477471 |
| 25 | 41478716501 |
| 26 | -8529964147714967 |
| 27 | -3818348299 |
| 28 | -2610006147952249 |
| 29 | 36698180928319 |