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 | 0 |
| 1 | 5 |
| 2 | -7 |
| 3 | 27 |
| 4 | -84 |
| 5 | 240 |
| 6 | -630 |
| 7 | 1554 |
| 8 | -3702 |
| 9 | 8694 |
| 10 | -20310 |
| 11 | 47190 |
| 12 | -108684 |
| 13 | 247572 |
| 14 | -557928 |
| 15 | 1246320 |
| 16 | -2765760 |
| 17 | 6106944 |
| 18 | -13427424 |
| 19 | 29404704 |
| 20 | -64138560 |
| 21 | 139366080 |
| 22 | -301749888 |
| 23 | 651236352 |
| 24 | -1401444864 |
| 25 | 3007987200 |
| 26 | -6440578560 |
| 27 | 13759041024 |