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 | -3 |
| 2 | 8 |
| 3 | -24 |
| 4 | 70 |
| 5 | -204 |
| 6 | 596 |
| 7 | -1740 |
| 8 | 5080 |
| 9 | -14832 |
| 10 | 43304 |
| 11 | -126432 |
| 12 | 369136 |
| 13 | -1077744 |
| 14 | 3146624 |
| 15 | -9187008 |
| 16 | 26822752 |
| 17 | -78312768 |
| 18 | 228645056 |
| 19 | -667561152 |
| 20 | 1949037952 |
| 21 | -5690488320 |
| 22 | 16614174848 |
| 23 | -48507402240 |
| 24 | 141624130816 |
| 25 | -413491415808 |
| 26 | 1207245897728 |
| 27 | -3524722888704 |
| 28 | 10290920404480 |