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 | 18 |
| 3 | 135 |
| 4 | 1008 |
| 5 | 4815 |
| 6 | -38826 |
| 7 | -1199646 |
| 8 | -563904 |
| 9 | 519188373 |
| 10 | 3420802620 |
| 11 | -474196640841 |
| 12 | -4490175699792 |
| 13 | 845516022777504 |
| 14 | 3767994187790868 |
| 15 | -2565470448416339190 |
| 16 | 31376572722070203168 |
| 17 | 11396618210613478642335 |
| 18 | -523335368250939507824250 |