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 | 0 |
| 2 | 18 |
| 3 | 480 |
| 4 | 11550 |
| 5 | 275184 |
| 6 | 6597360 |
| 7 | 159629184 |
| 8 | 3897563670 |
| 9 | 95946708000 |
| 10 | 2378998624860 |
| 11 | 59359563244800 |
| 12 | 1489281975509328 |
| 13 | 37545821365718400 |
| 14 | 950601539891016000 |
| 15 | 24159023128878865920 |
| 16 | 616066120184552310150 |
| 17 | 15757649689979967739200 |