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 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 5 |
| 6 | 18 |
| 7 | 42 |
| 8 | -58 |
| 9 | -1664 |
| 10 | -14502 |
| 11 | -90574 |
| 12 | -382846 |
| 13 | 114556 |
| 14 | 26040038 |
| 15 | 376126350 |
| 16 | 3773076517 |
| 17 | 28273327725 |
| 18 | 111536583430 |
| 19 | -1134493414034 |
| 20 | -36043045939893 |
| 21 | -581994648802655 |
| 22 | -7078387642902232 |
| 23 | -63895288842031656 |
| 24 | -248139475138765108 |
| 25 | 6030827802781277326 |