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 | 0 |
| 3 | -54 |
| 4 | -324 |
| 5 | -972 |
| 6 | 0 |
| 7 | 17496 |
| 8 | 104976 |
| 9 | 314928 |
| 10 | 0 |
| 11 | -5668704 |
| 12 | -34012224 |
| 13 | -102036672 |
| 14 | 0 |
| 15 | 1836660096 |
| 16 | 11019960576 |
| 17 | 33059881728 |
| 18 | 0 |
| 19 | -595077871104 |
| 20 | -3570467226624 |
| 21 | -10711401679872 |
| 22 | 0 |
| 23 | 192805230237696 |
| 24 | 1156831381426176 |
| 25 | 3470494144278528 |