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 | -1 |
| 5 | -1 |
| 6 | -1 |
| 7 | -1 |
| 8 | 34 |
| 9 | 125 |
| 10 | 335 |
| 11 | 791 |
| 12 | -4027 |
| 13 | -41328 |
| 14 | -223510 |
| 15 | -966174 |
| 16 | -1082043 |
| 17 | 22493107 |
| 18 | 255137121 |
| 19 | 1853859145 |
| 20 | 8611832136 |
| 21 | 6734302429 |
| 22 | -364364045001 |
| 23 | -4974309134233 |
| 24 | -41550393316275 |
| 25 | -223452696895652 |
| 26 | -173393115915136 |
| 27 | 14282249293678744 |