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 | -7 |
| 5 | -39 |
| 6 | -119 |
| 7 | 841 |
| 8 | 10641 |
| 9 | 59473 |
| 10 | -393679 |
| 11 | -9119439 |
| 12 | -77841719 |
| 13 | 453247081 |
| 14 | 17769103353 |
| 15 | 210702481081 |
| 16 | -1002688100959 |
| 17 | -65813075987679 |
| 18 | -1022777654395679 |
| 19 | 3554736409105633 |
| 20 | 413233827275657241 |
| 21 | 8091508938651283321 |
| 22 | -16214426267734966039 |