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 | 1840 |
| 3 | 88320 |
| 4 | 4152880 |
| 5 | 195187200 |
| 6 | 9173800240 |
| 7 | 431168613120 |
| 8 | 20264924818480 |
| 9 | 952451466470400 |
| 10 | 44765218924110640 |
| 11 | 2103965289433201920 |
| 12 | 98886368603360492080 |
| 13 | 4647659324357943129600 |
| 14 | 218439988244823327093040 |
| 15 | 10266679447506696373374720 |