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 | 1 |
| 3 | 0 |
| 4 | -34 |
| 5 | 35 |
| 6 | 0 |
| 7 | 11056 |
| 8 | -16830 |
| 9 | 5775 |
| 10 | 0 |
| 11 | -14873104 |
| 12 | 27560780 |
| 13 | -15315300 |
| 14 | 2627625 |
| 15 | 0 |
| 16 | 56814228736 |
| 17 | -119412815760 |
| 18 | 84786627900 |
| 19 | -24734209500 |
| 20 | 2546168625 |
| 21 | 0 |
| 22 | -495812444583424 |
| 23 | 1140896479608800 |
| 24 | -948030209181000 |
| 25 | 364143337057500 |
| 26 | -65706427536750 |
| 27 | 4509264634875 |