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 | -29 |
| 6 | -179 |
| 7 | -629 |
| 8 | -1679 |
| 9 | 52921 |
| 10 | 672841 |
| 11 | 4352041 |
| 12 | 19934641 |
| 13 | -656794709 |
| 14 | -13394641259 |
| 15 | -130483743389 |
| 16 | -870226287839 |
| 17 | 29354743432561 |
| 18 | 855880592510161 |
| 19 | 11361346027482961 |
| 20 | 101129588155349281 |
| 21 | -3446498927212733069 |
| 22 | -134465010284782027619 |