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 | 6 |
| 2 | 36 |
| 3 | 222 |
| 4 | 1440 |
| 5 | 9990 |
| 6 | 74880 |
| 7 | 609390 |
| 8 | 5391360 |
| 9 | 51798150 |
| 10 | 539136000 |
| 11 | 6060383550 |
| 12 | 73322496000 |
| 13 | 951480217350 |
| 14 | 13198049280000 |
| 15 | 195053444556750 |
| 16 | 3061947432960000 |
| 17 | 50908949029311750 |
| 18 | 894088650424320000 |