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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | -1 |
| 5 | 7 |
| 6 | -7 |
| 7 | 199 |
| 8 | -71 |
| 9 | 484 |
| 10 | -368 |
| 11 | 187909 |
| 12 | -610103 |
| 13 | 2068657 |
| 14 | -63614 |
| 15 | 1530164189 |
| 16 | -1715846683 |
| 17 | 7628902283 |
| 18 | -125125345078 |
| 19 | 9521826231889 |
| 20 | -17921564328719 |
| 21 | 291162274608871 |
| 22 | -47147385565688 |
| 23 | 552647133893696333 |
| 24 | -36898601487519532 |
| 25 | 4761064630028162378 |