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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 60 |
| 4 | 2520 |
| 5 | 453600 |
| 6 | 59875200 |
| 7 | 13621608000 |
| 8 | 8009505504000 |
| 9 | 3123380227968000 |
| 10 | 1832279324908032000 |
| 11 | 2054813830468439040000 |
| 12 | 1665031453088810526720000 |
| 13 | 1925086583971531588608000000 |