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 | -2 |
| 2 | 6 |
| 3 | -17 |
| 4 | 48 |
| 5 | -136 |
| 6 | 385 |
| 7 | -1090 |
| 8 | 3086 |
| 9 | -8737 |
| 10 | 24736 |
| 11 | -70032 |
| 12 | 198273 |
| 13 | -561346 |
| 14 | 1589270 |
| 15 | -4499505 |
| 16 | 12738896 |
| 17 | -36066072 |
| 18 | 102109441 |
| 19 | -289089922 |
| 20 | 818464798 |
| 21 | -2317218881 |
| 22 | 6560457280 |
| 23 | -18573817120 |
| 24 | 52585767681 |
| 25 | -148879626882 |
| 26 | 421504606246 |
| 27 | -1193354233937 |
| 28 | 3378597307248 |