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 | -1 |
| 2 | 2 |
| 3 | 18 |
| 4 | 64 |
| 5 | 160 |
| 6 | 288 |
| 7 | 224 |
| 8 | -1024 |
| 9 | -6912 |
| 10 | -28160 |
| 11 | -95744 |
| 12 | -294912 |
| 13 | -851968 |
| 14 | -2351104 |
| 15 | -6266880 |
| 16 | -16252928 |
| 17 | -41222144 |
| 18 | -102629376 |
| 19 | -251527168 |
| 20 | -608174080 |
| 21 | -1453326336 |
| 22 | -3437232128 |
| 23 | -8055160832 |
| 24 | -18723373056 |
| 25 | -43201331200 |
| 26 | -99019128832 |
| 27 | -225586446336 |