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 | 1 |
| 4 | 1 |
| 5 | -7 |
| 6 | -47 |
| 7 | -223 |
| 8 | -895 |
| 9 | -2959 |
| 10 | -31 |
| 11 | 82721 |
| 12 | 1002497 |
| 13 | 8156073 |
| 14 | 53580465 |
| 15 | 239061825 |
| 16 | -8587007 |
| 17 | -19348243487 |
| 18 | -305732208959 |
| 19 | -3454706477375 |
| 20 | -30437638147583 |
| 21 | -182295608480935 |
| 22 | 144862063593105 |
| 23 | 26905043182243041 |